,==y^O  Aii/O  ri)epartyyient  of  ^ 

LIBRARY  OF  fl 

I  Illinois  Indiistria]  University,  ^ 

0:;j*   Books  are  not  to  be  taken  from  the  Librarv  Room.    ^;iO  I  ' 


REMOTE  STORAGE 


UMIVERSiTY  OF 

ILLINOIS  Library 

AT  URBANA-CHAMPAlGll 


A 

OF  THE  PRINCIPAIi 

INSTEUMENTS 

USED  IN 

AMERICAN  ENGINEERING  AND  SURVEYING. 


MANT7FACTURBD  BY 


TROY,  N.  Y.: 

PUBLISHED  BY  W.  &  L.  E.  GURLEY. 
1870. 


4 


/i 

Entered  according  to  Act  of  Congress,  in  the  year  ldS2, 
BY  W.  <fe  L.  E.  GTTRJ;EY, 
Sn  the  Clerk's  Office  of  the  District  Court  for  the  Northern  District  of 
New  York. 

REMOTE  ST^- AGE 


BENJ.  D.  BENSON, 

PRINTER  AND  STATIONBB, 

60  Liberty  streety  N.  Y. 


I>RICE  LIST, 

Troy,  Oct.  1st,  1870. 


All  prices  in  this  work  are  in  U.  S.  currency. 


COMPASSES. 

Plain,  with  Jacob  Staff  mountings,  4  inch  needle   $30  00 

5        "    35  00 

"              *'         6    40  00 

Vernier,            "              *'        4        "    40  00 

"                        5         "    45  00 

"              "        6        "    50  00 

Railroad,       \    "              "        single  vernier  to  limb,  5  inch  needle   65  00 

/   "               "            "               "           5i                ....  70  00 

"            /    "              "        double          "          5^               ....  80  00 

Extras. 

Compass  tripod,  with  cherry  legs   8  00 

**             "    leveling  screws  and  clamp  and  tangent  movements. . .  18  00 

"           mountings  without  legs   7  00 

Compound  tangent  ball   6  00 

Adjusting  socket   4  00 

Jacob  Staff  mountings,  brass  head   2  50 

"               "         steel  point   0  60 

Brass  cover  for  compass  glass   1  00 

Outkeeper  for  keeping  tally     1  00 

TRANSITS. 

Vernier,  plain  telescope,*  4  inch  needle,  with  compass  tripod   75  00 

5       "             "            "    80  00 

"                "            6       "                          "    85  00 

Surveyor's       "            4  inch  single  vernier  to  limb,  adjusting  tripod   135  00 

"              "            5       "            »                         i4           _  140  00 

"              "            5^     "            "         "                "           ....  140  00 

"              "            4  inch  double  vernier  to  limb,         "    160  00 

*'               *'            5       "             .1         u                 41  105  00 

"               "            5i      "             u         u                 u  jgg  00 

Engineers'       **            4  inch  double  vernier  to  limb   175  00 

V               "        •     5       "             u         u                 u  180  00 

"              "            5  inch,  with  watch  telescope   220  00 

"              "            5  inch,  with  theodolite  axis   220  00 


*  A  "plain"  telescope  is  one  without  any  of  the  attachments  or  extras,  as  we 
term  them,  such  as  the  clamp  and  tangent,  vertical  circle  and  level. 


4  PRICE  LIST. 


lExtras  to  Transits. 

Vertical  circle,  3i  inch  diameter,  vernier  reading  to  five  minutes   $8  00 

"           4i          "              "          "          single  "    14  00 

Clamp  and  tangent  movement  to  axis  of  telescope   7  00 

Level  on  telescope,  with  ground  bubble  and  scale.   14  00 

Rack  and  pinion  movement  to  eye-glass   5  00 

Sights  on  telescope,  with  folding  joints   8  00 

Sights  on  standards  at  right  angles  to  telescope   8  00 

SOLAR  COMPASSES. 

Solar  compass,  with  adjusting  sockets  and  tripod   210  00 

Solar  telescope  compass,  with  adjusting  socket  and  leveling  tripod   235  00 

Micrometer  telescope,  16  to  20  inches  long,  with  rack  movement  to  object- 
glass,  and  with  movable  clips  to  attach  the  sights  to  No.  1   25  00 

LEVELING   RODS,  &c. 

Yankee  or  Boston   16  00 

New  York,  with  improved  mountings    16  00 

Mountings  for  New  York  rod,  target   5  50 

"                  "         "    clamp   2  50 

LEVELING  INSTRUMENTS. 

Sixteen-inch  telescope,  with  adjusting  tripod   135  00 

Eighteen         "             "               "    135  00 

Twenty          "             "               "   135  00 

Twenty-two  inch  telescope              "   135  00 

Fifteen-inch  dumpy,  or  builder's  level,  with  adjusting  tripod   75  00 

Eleven          "                  "               "             "    60  00 

"                               "            with  adjusting  socket  and  tripod   55  00 

CHAINS. 

100  feet,  with  oval  rings,  No.  5  refined  iron  wire   12  00 

6                "    9  00 


50  feet,  " 

41 

(( 

50  feet,  " 

6  " 

5  00 

66  feet,  " 

8  " 

4( 

33  feet,  " 

8  " 

2  75 

66  feet,  " 

(( 

10  " 

H 

33  feet,  " 

(( 

10  » 

It 

2  50 

100  feet,  " 

100  feet,  " 

(( 

10  " 

50  feet,  " 

(I 

8  " 

6  50 

50  feet,  " 

u 

10 

tt 

5  75 

66  feet,  " 

8  " 

it 

66  feet,  " 

a 

10  " 

8  00 

33  feet, 

it 

8  " 

« 

5  75 

33  feet,  " 

li 

10  " 

il 

4  50 

100  feet,  brazed  links  and  rings.  No.  12  best  steel  wire,  tempered  

...     15  00 

50  feet,  " 

12 

tl 

8  00 

66  feet,  " 

12 

tl 

14  00 

33  feet,  " 

(( 

32 

t4 

PRICE  LIST. 


5 


CI  r ixmina/H  X^ateiit  Cliaiiis. 

Drag  Chains. 


66  feet,  No.  15  tempered  steel  wire,  100  links,  weight  li  lbs   $10  00 

With  10  extra  links. 

33      "       15       "            "         50    "          "     I  "    6  00 

With  5  extra  links. 

100      "       15       "            "        200    "          "    2    "    14  00 

With  15  extra  links. 

50      "       15                    "        100    "          u     1    "    8  00 

With  10  extra  links. 

33  feet,  No.  12  wire,  5  tallies,  with  5  extra  links,  weighs  1\%  lbs   7  00 

66      "       12    "  10         "        10                             3     "    14  00 

50      "       12    "    5         "         5        "             "      2i    "    8  00 

100      "       12    "  10         "        10        "             "      4i    "    15  00 

Spring  balance  to  use  with  either  of  the  above-named  chains   5  00 

60  feet,  No.  18  tempered  steel  wire,  100  links,  no  rings,  with  attachments  of 
spring-balance,  level,  and  thermometer,  for  very  accurate  measurements, 

weight  I  lbs   25  00 

Set  of  10  marking  pins,  very  light,  with  leather  case   1  50 

Brass  plummet,  Jo  use  with  light  chain    2  00 

Lead       "    1  50 

MARKING  PINS. 

Set  of  11  pins,  iron  wire,  No.  4   1  50 

"      "       steel  wire.  No.  6   2  00 

"      "      brass  wire,  No.  4   3  00 

MEASURING-  TAPES. 

Chesterman's  steel,  33  feet   9  00 

"    50  feet   12  50 

"66  feet   15  50 

"            "  100  feet   22  00 

"     metallic,  33  feet   3  25 

"                 50  feet   4  25 

"            "    66  feet   4  75 

•»            "    70  feet   5  25 

"            "    80  feet   6  00 

"            "  100  feet   6  75 

POCKET  COMPASSES. 

With  folding  sights,  2^  inch  needle,  very  serviceable  for  tracing  lines  once 

surveyed   9  00 

With  folding  sights,  2^  inch  needle,  with  Jacob  staff  mountings   11  50 

3i         "                     "               "    13  50 

"       "        "     3i        "           "         "              "    and  two  levels  15  00 

"       "        "     3|        "         without  mountings  or  levels   1100 

Vernier  pocket  compass,  with  staff  mountings,  two  levels,  and  3i  inch  needle  18  00 

Pocket  compasses  without  sights  see  Supplement. 

Miners'  compass,  or  dipping  needle,  for  tracing  iron  ore,  a  new  and  beautiful 

article,  glass  on  both  sides   10  00 

Miners'  compass,  or  dipping  needle,  with  stop  to  needle   12  00 

DRAWING  INSTRUMENTS. 

French  and  German  see  Supplement,  &c. 

Swiss   " 

Drawing,  profile,  and  cross-section  paper   " 

Colors,  pencils,  ink,  brushes,  &c   " 

Books  on  engineering  and  surveying   " 

Telescopes,  microscopes,  opera-glasses,  &c  


Information  to  Fnrcliasers. 


Instruments  "Wanted — In  regard  to  the  best  kind  of  instruments  fot 
particular  purposes,  we  would  here  say,  that  where  only  common  sur- 
veying, or  the  bearing  of  lines  in  the  surveys  for  county  maps  is  required, 
a  plain  compass  is  all  that  is  necessary.  In  cases  where  the  variation 
of  the  needle  is  to  be  allowed,  as  in  retracing  the  lines  of  an  old  survey, 
&c.,  the  vernier  compass  or  the  vernier  transit  is  required. 

Where,  in  addition  to  the  variation  of  the  needle,  horizontal  angles 
are  to  be  taken,  and  in  cases  of  local  attraction,  the  railroad  compass  is 
preferable;  and  for  a  mixed  practice  of  surveying  and  engineering,  we 
consider  the  surveyor's  transit  superior  to  any  instrument  made  by  us 
or  any  other  manufacturers. 

In  the  surveys  of  U.  S.  public  lands,  the  county  and  township  lines 
are  required  to  be  run  by  such  instruments  as  the  solar  compass. 

Where  engineering  is  the  exclusive  design,  the  engineer's  transit  and 
the  leveling  instrument  are  of  course  indispensable. 

The  builders'  level  is  intended  for  laying  out  mill  seats  and  determining 
the  levels  of  buildings  in  course  of  erection. 

Warranty. — All  our  instruments  are  examined  and  tested  by  us  in 
person,  and  are  sent  to  the  purchaser  adjusted  and  ready  for  immediate 
use. 

They  are  warranted  correct  in  all  their  parts — we  agreeing  in  the  event 
of  any  defect  appearing  after  reasonable  use,  to  repair  or  replace  with  a 
new  and  perfect  instrument,  promptly  and  at  our  own  cost,  express 
charges  included,  or  we  will  refund  the  money  and  the  express  charges 
paid  by  the  customer. 

Instances  may  sometimes  occur,  in  a  business  as  large  and  widely 
extended  as  ours,  where,  owing  to  careless  transportation,  or  to  defects 
escaping  the  closest  scrutiny  of  the  maker,  instruments  may  reach  our 
customers  in  bad  condition.  We  consider  the  retention  of  such  instru- 
ments in  all  cases  an  injury  very  much  greater  to  us  than  to  the  pur- 
chaser himself. 


INFORMATION  TO  PURCHASERS. 


7 


Trial  op  Instruments. — It  may  often  happen  that  this  statement  of 
tb^  prices  and  quality  of  our  instruments  may  come  into  the  hands  of 
those  who  are  entirely  unacquainted  with  us,  or  with  the  quality  of  our 
work,  and  who  therefore  feel  unwilling  to  make  a  final  purchase  of  an 
Article,  of  the  excellence  of  which  they  are  not  perfectly  assured. 

To  such  we  make  the  following  proposition:  We  will  send  the  instru- 
ment to  the  express  station  nearest  the  person  giving  the  order,  and 
direct  the  express  agent,  on  delivery  of  the  same,  to  collect  our  bill, 
together  with  charges  of  transportation,  and  hold  the  money  on  deposit 
until  the  purchaser  shall  have  had, say  two  weeks, actual  trial  of  its  quality. 

If  not  found  as  represented,  he  may  return  the  instrument  before  the 
expiration  of  that  time,  and  receive  the  money  paid,  in  full,  including 
express  charges,  and  direct  the  instrument  to  be  returned  to  us. 

Extent  of  our  Business. — The  manufacture  of  surveying  instruments 
has  been  conducted  by  us  over  twenty-five  years,  and  thousands  of  our 
instruments  have  been  distriDuted  to  customers  in  all  parts  of  the  United 
States  and  Canadas;  in  Cuba,  South  America  and  the  Sandwich  Islands. 

Our  facilities  for  manufacturing,  which  for  many  years  have  been  far 
superior  to  those  of  any  other  similar  establishment,  we  have  now  (1870) 
greatly  increased  by  the  introduction  of  new  machinery  and  tools  Of  the 
most  improved  construction.  Our  manufactory  has  been  re-built  of 
nearly  three  times  its  former  size,  and  we  are  better  prepared  than  ever 
before  to  fill  orders  for  any  of  our  instruments  with  promptness  and  satis- 
faction. 

Low  Prices  of  our  Instruments. — It  is  often  urged  by  other  makers, 
and  persons  prejudiced  in  their  favor,  that  it  is  impossible  to  make  first 
rate  instruments  at  the  prices  charged  by  us,  and  which  are  so  very  far 
below  those  of  other  skillful  manufacturers. 

We  have  only  to  reply,  in  addition  to  what  we  have  stated  in  our  war- 
ranty, that  a  visit  to  our  works,  and  a  comparison  of  our  facilities,  with 
those  of  our  competitors,  would  dispel  all  questions  as  to  our  ability  to 
surpass  them,  not  only  in  the  cheapness,  but  also  in  the  superior  quality 
of  our  work. 

.  Packing,  &c. — Each  instrument  is  packed  in  a  well  finished  mahogany 
case,  furnished  with  lock  and  key  and  brass  hooks,  the  larger  ones  hav- 
ing besides  these,  a  leather  strap  for  conyenience  in  carrying.  Each  case 
is  provided  with  screw  drivers,  adjusting  pin,  and  wrench  for  centre  pin, 
and,  if  accompanied  by  a  tripod,  with  a  brass  plumb-bob;  with  all  instru- 
ments for  taking  angles,  without  the  needle,  a  reading  microscope  is  also 
furnished . 


8 


INFORMATION  TO  PURCHASERS. 


Unless  the  purchaser  is  already  supplied,  each  Instrument  is  accom- 
nied  by  our  "  Manual,"  giving  full  instructions  for  such  adjustments  and 
repairs  as  are  possible  to  one  not  provided  with  the  facilities  of  an  instru- 
ment maker. 

When  sent  to  the  purchaser,  the  mahogany  cases  are  carefully  enclosed 
in  outside  packing  boxes,  of  pine,  made  a  little  larger  on  all  sides  to 
allow  the  introduction  of  elastic  material,  and  so  effectually  are  our  instru- 
ments protected  by  these  precautions,  that  of  several  thousand  sent  out 
by  us  during  the  last  twenty  years,  in  all  seasons,  by  every  mode  of 
transportation,  and  to  all  parts  of  the  Union  and  the  Canadas,  not  more 
than  three  or  four  have  sustained  any  serious  injury. 

Means  of  Transportation. — Instruments  can  be  sent  by  express  to 
almost  every  town  in  the  United  States  and  Canadas,  regular  agents 
being  located  at  all  the  more  important  points,  by  whom  they  are  for- 
warded to  smaller  places  by  stage.  The  charges  of  transportation  from 
Troy  to  the  purchaser  are  in  all  cases  to  be  borne  by  him,  we  guaran- 
teeing the  safe  arrival  of  our  instruments  to  the  extent  of  express  trans-, 
portation,  and  holding  the  express  companies  responsible  to  us  for  all 
losses  or  damages  on  the  way. 

Finish  op  Instruments. — Customers  ordering  instruments,  will  do  us  a 
favor  by  mentioning  whether  they  prefer  them  of  bright,  or  bronze  finish, 
the  cost  being  the  same  in  either  case. 

If  no  direction  is  given,  we  usually  send  instruments  finished  bright. 

Terms  of  Payment  are  uniformly  cash,  and  we  have  but  one  price, 
whether  ordered  in  person  or  by  mail.  Our  terms  are  as  low  as  we  think 
instruments  of  equal  quality  can  be  made,  and  will  not  be  varied  from  the 
list  given  on  the  previous  pages. 

Remittances  may  be  made  by  a  draft,  payable  to  our  order  at  Troy, 
Albany,  New  York,  Boston  or  Philadelphia,  which  can  be  procured  from 
banks  or  bankers  in  almost  all  the  larger  villages,  or  by  post  office  money 
order. 

These  may  be  sent  by  mail  with  the  order  for  the  instrument,  and  if 
lost  or  stolen  on  the  route,  can  be  replaced  by  a  duplicate  draft,  obtained 
as  before,  and  without  additional  cost. 

The  customer  may  also  send  the  money  in  advance  through  the  express 
agent,  or  as  is  most  common,  may  pay  the  agent  on  receipt  of  the  instru- 
ment in  funds  current  in  New  York  or  Boston. 

The  cost  of  returning  the  money  on  bills  collected  by  express  of  amountfl 
under  $20,  will  be  charged  to  the  customer. 


INFORMATION  TO  PURCHASERS. 


9 


REPAIR  OF  INSTRUMENTS. 


Hundreds  of  instruments  of  our  own  and  others'  make,  come  to  us  every 
year  for  refitting  and  repairs,  and  so  much  correspondence  arises  therefrom, 
that  we  are  led  to  believe  that  a  brief  statement  in  this  place,  of  the  cost 
of  such  repairs,  &c.,  will  be  of  service  to  our  customers  and  ourselves. 

Most  instruments  sent  tons  for  repairs  are  injured  by  falls;  many  are 
worn  and  defective  in  parts  after  long  use ;  and  others  are  sent  for  repolish- 
ing  and  renovation. 

We  advise  our  customers  having  instruments  in  need  of  repairs,  &c.,  to 
gend  them  immediately  to  us,  as  our  facilities  enable  us  to  do  the  work 
much  more  economically  and  promptly  than  any  other  maker  however  ac- 
cessible. 

They  should  always,  when  practicable,  be  placed  in  their  own  boxes,  and 
these  inclosed  in  an  outside  packing  case,  an  inch  larger  in  all  its  dimen- 
sions, that  the  interval  between  the  two  may  be  filled  with  paper  wadding, 
hay  or  fine  shavings. 

A  note  specifying  the  repairs  needed,  should  accompany  the  instrument, 
and  a  letter  should  also  be  sent  by  mail  to  us,  giving  not  only  directions  as 
to  the  repairs,  but  also  stating  when  the  return  of  the  instrument  is  re- 
quired, and  the  precise  location  to  which  it  should  be  forwarded.  It  should 
also  be  remembered  that  each  instrument  is  made  to  fit  its  own  spindle  and 
no  other;  and  therefore  this  part  with  the  parallel  plates  and  leveling 
screws,  if  it  has  any,  should  always  be  sent  with  it. 

The  legs  and  brass  head  in  which  they  are  inserted  need  never  be  sent, 
unless  themselves  in  need  of  repairs. 

Compasses. — These  come  to  us  with  the  plates  sprung,  the  sights  bent 
or  broken,  the  glass  or  level  vials  fractured,  and  the  pivot  so  dulled  as  to 
render  the  needle  sluggish  and  unreliable.  The  cost  of  repairing  the  de- 
fects above  named,  ranges  from  2  to  8  or  10  dollars.  A  new  pair  of  sights 
fitted  costs  5  dollars;  a  new  needle,  with  jeweled  centre  and  pivot  com- 
plete, $2.50;  a  new  jeweled  centre,  $1.50. 

The  compass  should  always  be  accompanied  by  the  ball  spindle,  and  if  a 
new  ball  spindle  is  required,  the  whole  instrument,  or  at  least  the  socket  in 
which  the  spindle  fits,  should  be  sent  with  the  letter  of  advice  to  us;  a  new 
ball  spindle  costs  two  dollars. 

Transit  Instruments. — The  repairs  of  the  Vernier  Transits  cost  about 
the  same  as  those  of  the  compasses  above  stated. 

The  injuries  sustained  by  the  falls  of  Engineers'  and  Surveyors'  Transit! 
%re  usually  much  more  serious;  in  these  the  plates,  standards  and  cross- 


10 


INFORMATION  TO  PURCHASERS. 


bar  of  telescope  are  often  bent,  and  the  sockets  or  centres  usually  so  de- 
ranged as  to  be  entirely  useless. 

The  cost  of  repairing  an  instrument  with  such  injuries,  ranges  from  10 
to  30  or  even  50  dollars,  the  new  sockets  alone  costing  from  10  to  20  dollars. 

Leveling  Instruments  are  generally  much  less  injured  by  falling  than 
Transits,  the  damages  being  included  usually  in  the  bending  of  the  cross- 
bar, the  springing  of  the  sockets,  and  the  breaking  of  the  level  vial. 

The  cost  of  repairs  varies  from  6  to  15  dollars ;  a  new  level  vial  set  in  the 
tube  costs  two  dollars. 

Re -POLISHING  Instruments. — The  cost  of  re -polishing  an  instrument, 
involving  also  of  course  its  complete  renovation  and  adjustment,  varies  with 
the  different  kinds,  but  may  be  stated  generally  as  follows : 

Compasses,  from   $5  to  $A 

Transits        do    10  to  16 

Levels  do      10  to  13 

No  additional  charge  is  made  for  bronzing  or  blackening  an  instrument 
when  re -polished. 

Payment  of  Repairs,  &c.,  may  be  made  at  the  express  oflBce  where 
tbe  instrument  is  received,  the  customer  paying  for  the  first  transportation 
of  the  instruments  to  us  or  not  as  he  may  prefer.  Whenever  the  freight  is 
paid  in  advance,  the  express  receipt  should  be  mailed  immediately  to  us. 

W.  &  L.  E.  GURLEY, 
Mathematical  Instrument  Makers^ 
FuLTOw  1*    opposite  North  End  op  Union  R.  R.  Depot,  Troy,  N.  Y» 


Preface  to  the  Sixteenth  Edition. 


 . 

We  herewitli  present  the  Engineers  and  Surveyors  of 
the  Union,  this  new  edition  of  our  little  work,  materially 
enlarged,  and,  as  we  trust,  improved. 

We  are  now  (October,  1870),  much  better  furnished  with 
facilities  of  all  kinds  to  prosecute  with  enlarged  success  the 
business  to  which  we  have  devoted  over  twenty-five  years. 

It  is  with  the  hope,  therefore,  that  we  shall  still  further 
enlarge  the  list  of  our  many  patrons  and  friends  in  this  and 
in  other  countries,  and  that  this  description  of  our  instru- 
ments may  be  of  increasing  service  to  the  Surveyor  and 
Engineer,  that  we  now  commit  it  to  their  indulgence. 

W.  &  L.  E.  GUELEY. 

Troy,  October,  1870. 


Surveying  Instrumeiits. 

The  various  instruments  us^'in  Surveying  may  be  conve- 
niently arranged,  into  two  general  divisions. 

(1.,)  Needle  instruments,— or  such  as  owe  their  accuracy 
and  value  to  the  magnetic  needle  only,  embracing  the  Plain 
and  Yernier  compasses,  and  the  Vernier  Transit. 

(2.)  Angular  instruments,  including  those  in  which  the 
horizontal  angles,  are  measured  by  a  divided  circle  and  ver- 
niers, as  well  as  by  the  needle  also;  as  the  Eailroad  Com- 
pass, the  Surveyors^  and  Engineers'  Transits,  &c. 

In  the  present  work  we  shall  consider  first,  those  instru- 
ments comprised  in  the  first  division,  and,  as  in  these  the 
accuracy  of  the  horizontal  angles  indicated,  depends  upon 
the  delicacy  of  the  needle,  and  the  constancy  with  which  it 
assumes  a  certain  direction,  termed  the  magnetic  meridian,'' 
we  shall  here  remark  briefly  upon  the  form^  the  length,  and 
the  movement  of 

The  Magnetic  Needle. — The  forms  of  the  needle  are  almost 
infinitely  varied,  according  to  the  taste  or  fancy  of  the  maker 
or  surveyor,  but  may  be  resolved  into  two  general  classes, 
one  having  the  greatest  breadth  in  a  horizontal,  the  other  in 
a  vertical  direction. 

We  have  usually  made  our  needles  about  one-twei:  tieth  of 
an  inch  broad  and  one-third  as  thick,  parallel  from  end  to 
end,  the  north  and  south  poles  being  distinguished  from  each 
other,  by  a  small  scollop  on  the  north  end. 

Of  course  the  form  of  the  needle  is  always  varied  according 
to  the  choitjeof  our  customers,  and  without  additional  charge. 

The  length  of  the  needle  varies  in  different  instruments, 
from  four  to  six  or  even  seven  inches,  those  of  five  and  a  half, 
or  six  inches  long,  being  generally  preferred  by  surveyors. 

The  movement  of  the  needle,  with  the  least  possible  friction, 
is  secured  by  suspending  it,  by  a  steel  or  jewel  centre,  upon 


14' 


THE  PLAIN  COMPASS. 


a  hardened  stee^  pivot,  the  point  of  which  is  made  perfectly 
sharp  and  smooth. 

The  test  of  the  delicacy  of  a  magnetic  needle  is  the  num- 
ber of  horizontal  vibrations,  which  it  will  make  in  a  certain 
arc,  before  coming  to  rest — besides  this  most  surveyors  pre- 
fer also  to  see  a  sort  of  quivering  motion  in  a  vertical  direction, 

This  quality,  which  is  manifested  more  in  a  horizontal, 
than  in  a  vertical  needle,  and  depends  upon  the  near  coinci- 
dence of  the  point  of  suspension  with  the  centre  of  gravity 
of  the  needle,  serves  to  show  merely  that  the  cap  below  is 
unobstructed. 

Having  now  considered  the  different  qualities  of  a  good 
needle,  we  shall  proceed  to  speak  of  those  instruments  of 
which  it  makes  so  important  a  part;  of  these,  the  most  sim- 
ple is  that  termed  the 

PLAIN  COMPASS. 
Fig.  1. 


As  represented  above,  the  Plain  Compass  has  a  needle  six 


THE  PLAIN  COMPASS. 


15 


inches  long",  a  graduated  circle,  main  plate,  levels  and  sights, 
and  is  placed  upon  the  brass  head  of  the  "  Jacob  staff.'' 

The  Compass  Circle  in  this,  as  in  all  our  instrun>ents,  is 
divided  to  half  degrees  on  its  upper  surface,  the  whole  degree 
marks  being  also  cut  down  on  the  inside  circumference,  and 
is  figured  from  0  to  90,  on  each  side  of  the  centre  or  "  line 
of  zeros/' 

The  circle  and  face  of  the  compass  are  silvered. 

The  Spirit  Levels  are  placed  at  right  angles  to  each  other 
so  as  to  level  the  plate  in  all  directions,  and  are  balanced 
npon  a  pivot  underneath  the  middle  of  the  tube,  so  as  to  be 
adjustable  by  a  common  screw-driver. 

The  Sights,  or  standards,  have  fine  slits  cut  through  nearly 
their  whole  length,  terminated  at  intervals  b}^  large  circular 
apertures,,  through  which  the  object  sighted  upon  is  more 
readily  found.  Sometimes  a  fine  horse-hair  or  wire  is  sub- 
'  stituted  for  one  half  the  slit,  and  placed  alternately  with  it 
on  opposite  sights. 

Tangent  Scale. — The  right  and  left  hand  edges  of  the 
sights  of  our  compasses,  have  respectively  an  eye-piece,  and 
a  series  of  divisions,  by  which  angles  of  elevation  and  de- 
pression, for  a  range  of  about  twenty  degrees  each  way,  can 
be  taken  with  considerable  accuracy. 

Such  an  arrangement  is  very  properly  termed  a  tangent 
scale,"  the  divided  edges  of  the  north  sight,  being  tangents 
to  segments  of  circles  having  their  centres  at  the  eye-pieces, 
and  their  points  of  contact  with  the  tangent  lines  at  the  zero 
divisions  of  the  scale. 

The  cut  shows  the  eye-piece  and  divisions  for  angles  of  de- 
pression; those  for  angles  of  elevation,  concealed  in  this  cut, 
are  seen  in  that  of  the  Railroad  Compass. 

The  Jacob  Staff  mountings  which  are  furnished  with  all 
our  compasses,  and  packed  in  the  same  case,  consist  of  the 


16 


THE  PLAIN  COMPASS. 


brass  head  already  mentioned,  and  an  iron  ferule  or  shoe, 
pointed  with  steel,  so  as  to  be  set  firmly  in  the  ground. 

The  staff,  to  which  the  mountings  should  be  securel}^  fas- 
tened, is  procured  from  any  wheelwright,  or  selected  by  the 
Burveyor  himself  from  a  sapling  of  the  forest. 

To  adjust  the  Compass. 
The  Levels. — First  bring  the  bubbles  into  the  centre,  hy 
the  pressure  of  the  hand  on  different  parts  of  the  plate,  and 
then  turn  the  compass  half  way  around  ;  should  the  bubbles 
run  to  the  end  of  the  tubes,  it  would  indicate  that  those  ends 
were  the  highest ;  lower  them  by  tightening  the  screws 
immediately  under,  and  loosening  those  under  the  lowest 
ends  until,  by  estimation,  the  error  is  half  removed  ;  level 
the  plate  again,  and  repeat  the  first  operation  until  the  bub- 
bles will  remain  in  the  center,  during  an  entire  revolution  of 
the  compass. 

The  Sights  may  next  be  tested  by  observing  through  the 
slits  a  fine  hair  or  thread,  made  exactly  vertical  by  a  plumb. 
Should  the  hair  appear  on  one  side  of  the  slit,  the  sight  niust 
be  adjusted  by  filing  off  its  under  surface  on  that  side  which 
seems  the  highest. 

The  Needle  is  adjusted  in  the  following  manner  :  Having 
the  eye  nearly  in  the  same  plane  with  the  graduated  rim  of 
the  compass  circle,  with  a  small  splinter  of  wood  or  a  slender 
iron  wire,  bring  one  end  of  the  needle  in  line  with  any  pro- 
minent division  of  the  circle,  as  the  zero,  or  ninety  degree 
mark,  and  notice  if  the  other  end  corresponds  with  the  degree 
on  the  opposite  side  ;  if  it  does,  the  needle  is  said  to  ''cut'' 
opposite  degrees  ;  if  not,  bend  the  centre-pin  by  applying  a 
small  brass  wrench,  furnished  with  our  compasses,  about 
one  eighth  of  an  inch  below  the  point  of  the  pin,  until  the 
ends  of  the  needle  are  brought  into  line  with  the  opposite 
degrees. 


THE  PLAIN  COMPASS 


17 


Then  holding  the  needle  in  the  same  position,  turn  the 
compass  half  way  around,  and  note  whether  it  now  cuts 
opposite  degrees  ;  if  not,  correct  half  the  error  by  bending 
the  needle,  and  the  remainder  by  bending  the  centre-pin. 

The  operation  should  be  repeated  until  perfect  reversion  is 
secured  in  the  first  position. 

This  being  obtained,  it  may  be  tried  on  another  quarter  of 
the  circle  ;  if  any  error  is  there  manifested,  the  correction 
mast  be  made  in  the  centre-pin  only,  the  netjdle  being  already 
straightened  by  the  previous  operation. 

When  again  made  to  cut,  it  should  be  tred  on  the  other 
quarters  of  the  circle,  and  corrections  made  in  the  same  man- 
ner until  the  error  is  entirely  removed,  and  Khe  needle  will 
reverse  in  every  point  of  the  divided  surface 

To  use  the  Compass. 
In  using  the  compass  the  surveyor  should  keep  the  south 
end  towards  his  person,  and  read  the  bearings  from  the  north 
end  of  the  needle.  He  will  observe  that  the  E  and  W  letters 
on  the  face  of  the  compass  are  reversed  from  their  natural 
position,  in  order  that  the  direction  of  the  line  of  sight  may  be 
correctly  read. 

The  compass  circle  being  graduated  to  half  degrees,  a 
little  practice  will  enable  the  surveyor  to  read  the  bearings 
to  quarters,  or  even  finer — estimating  with  his  eye  the  space 
bisected  by  the  point  of  the  needle,  and  as  this  is  as  low  as 
the  traverse  table  is  usually  calculated,  it  is  the  general 
practice. 

Sometimes,  however,  a  small  vernier  is  placed  upon  the 
Bouth  end  of  the  needle,  and  reads  the  circle  to  five  minutes 
of  a  degree — the  circle  being  in  that  case  graduated  to  whole 
degrees. 

This   contrivance,  however,  is  quite   objectionable  on 
account  of  the  additional  weight  imposed  on  the  centre-pin, 
2 


18 


THE  PLAIN  COMPASS. 


and  the  difficulty  of  reading  a  vernier  which  is  in  constant 
vibration,  and  is  therefore  but  little  used. 

To  TAKE  Angles  of  Elevation. — Having  first  leveled  the 
compass,  bring  the  south  end  towards  you,  and  place  the  eye 
at  the  little  button,  or  eye  piece,  on  the  right  side  cf  the  south 
sight,  and  with  the  hand  fix  a  card  on  the  front  surface  of  the 
north  sight,  so  that  its  top  edge  will  be  at  right  angles  to 
the  divided  edge,  and  coincide  with  the  zero  mark  ;  then 
sighting  over  the  top  of  the  card,  note  upon  a  flagstaff  the 
height  cut  by  the  line  of  sight ;  then  move  the  staff  up  the 
elevation,  and  carry  the  card  along  the  sight  until  the  line 
of  sight  again  cuts  the  same  height  on  the  staff,  read  off  the 
degrees  and  half  degrees  passed  over  by  the  card,  and  we 
shall  have  the  angle  required. 

For  Angles  of  Depression. — Proceed  in  the  same  manner, 
•using  the  eye-piece  and  divisions  on  the  opposite  sides  of  the 
sights,  and  reading  from  the  top  of  the  standards, 

Jacob  Staff  Socket. — The  compass  is  furnished  with  a 
ball  spindle,  or  socket,  upon  which  it  turns,  and  by  whitih  it 
is  levelled.  The  ball  may  be  placed  in  a  single  or  ''Jacob 
staff''  socket,  as  represented  in  the  figure,  or  in  a  compass 
tripod,  such  as  is  shown  in  the  cut  of  the  Vernier  Transit 
beyond. 

Clamp  Screw. — In  the  side  of  the  hollow  cylinder,  or  socket 
uf  the  compass,  which  fits  to  the  ball  spindle,  is  a  screw  by 
which  the  instrument  may  be  clamped  to  the  spindle  in  any 
position. 

Spring  Catch. — Besides  the  clamp  screw,  we  have  recently 
fitted  to  the  sockets  of  our  compasses  a  little  spring  catch, 
which,  as  soon  as  the  instrument  is  set  upon  the  spindle, 
slips  into  a  groove,  and  thus  removes  all  danger  of  falling 
when  the  instrument  is  carried. 

>^  eedle  Lifter. — There  is  also  underneath  the  main  plate,, 
a  needle  lifcing  screw  which,  by  moving  a  concealed  spring, 


THE  PLAIN  COMPASa 


19 


raises  the  needle  from  the  pivot,  and  thus  prevents  the  blunt- 
ing of  the  point  in  transportation. 

When  the  compass  is  not  in  use  it  is  the  practice  of  many 
surveyors  to  let  down  the  needle  upon  the  point  of  the  centre- 
pin,  and  let  it  assume  its  position  in  the  magnetic  meridian, 
so  as  to  retain  or  even  increase  its  polarity. 

We  would  advise  in  addition,  that  after  the  needle  has  set- 
tled it  should  be  raised  against  the  glass,  in  order  not  to  dull 
the  point  of  suspension. 

OuTKEEPER. — A  small  dial  plate,  having  an  index  turned  by 
a  milled  head  underneath,  is  often  used  with  this  and  the 
other  compasses  to  keep  tally  in  chaining. 

The  dial  is  figured  from  0  to  16,  the  index  being  moved  one 
notch  for  every  chain  run. 

Electricity. — A  little  caution  is  necessary  in  handling  the 
compass,  that  the  glass  covering  be  not  excited  by  the  fric- 
tion of  cloth,  silk,  or  the  hand,  so  as  to  attract  the  needle  to 
its  under  surface. 

A  brass  cover  is  sometimes  fitted  over  the  glass  of  the 
compass,  and  serves  to  protect  it  from  accident,  as  well  as 
V    to  prevent  electric  disturbance. 

When,  however,  the  glass  becomes  electric,  the  fluid  may 
be  removed  by  breathing  upon  it,  or  touching  di'^erent  parts 
of  its  surface  with  the  moistened  finger. 

An  ignorance  of  this  apparently  trifling  matter  has  caused 
many  errors  and  perplexities  in  the  practice  of  the  inexpe- 
rienced surveyor. 

Repairs  of  the  Compass, 

To  enable  the  surveyor  to  make  such  repairs  as  are  possi- 
ble without  having  recourse  to  an  instrument  maker,  we  here 
add  a  few  simple  directions. 

1.  The  Needle. — It  may  sometimes  happen  that  the  needle 


20 


THE  PLAIN  COMPASS. 


has  lost  its  polarity,  and  needs  to  be  re-magnetized;  this  is 
effected  in  the  following  manner: 

The  operator  being  provided  with  an  ordinary  permanent 
magnet,  and  holding  it  before  him,  should  pass  with  a  gentle 
pressure  each  end  of  the  needle  from  centre  to  extremity  over 
the  magnetic  pole,  describing  before  each  pass  a  circle  of 
about  six  inches  radius,  to  which  the  surface  of  the  pole  is 
tangent,  drawing  the  needle  towards  him,  and  taking  care 
that  the  north  and  the  south  ends  are  applied  to  the  opposite 
poles  of  the  magnet. 

Should  the  needle  be  returned  in  a  path  near  the  magnetic 
pole,  the  current  induced  by  the  contact  of  the  needle  and  mag- 
net, in  the  pass  just  described,  would  be  reversed,  and  thus  the 
magnetic  virtue  almost  entirely  neutralized  at  each  operation. 

When  the  needle  has  been  passed  about  twenty-five  times 
in  succession,  in  the  manner  just  described,  it  may  be  con- 
sidered as  fully  charged. 

A  fine  brass  wire  is  wound  in  two  or  three  coils  on  the 
south  end  of  the  needle,  and  may  be  moved  back  or  forth  in 
order  to  counterpoise  the  varying  weight  of  the  north  end. 

2.  The  Centre  Pin. — This  should  occasionally  be  examined, 
and  if  much  dulled,  taken  out  with  the  brass  wrench,  already 
spoken  of,  or  with  a  pair  of  plyers,  and  sharpened  on  a  hard 
oil  stone — the  operator  placing  it  in  the  end  of  a  small  stem 
of  wood,  or  a  pin  vice,  and  delicately  twirling  it  with  the  fin- 
gers as  he  moves  it  back  and  forth  at  an  angle  of  about  30 
deg.  to  the  surface  of  the  stone. 

When  the  point  is  thus  made  so  fine  and  sharp  as  to  be 
invisible  to  the  eye,  it  should  be  smoothed  by  rubbing  it  on 
the  surface  of  a  soft  and  clean  piece  of  leather. 

3.  To  PUT  IN  A  New  Glass. — Unscrew  the  ''bezzle  ring'^ 
which  holds  it,  and  with  the  point  of  a  knife  blade  spring 


*  A  magnet  suitable  for  this  purpose  costs  from  12  to  25  cents. 


THE  PLAIN  COMPASS. 


21 


out  the  little  brass  ring  above  the  glass,  remove  the  old 
glass  and  scrape  out  the  putty  ;  then  if  the  new  glass  does 
not  fit,  smooth  olf  its  edges  by  holding  it  obliquely  on  the 
surface  of  a  grind  stone  until  it  will  enter  the  ring  easily  ; 
then  put  in  new  putty,  spring  in  the  brass  ring,  and  the 
operation  will  be  complete. 

4.  To  REPLACE  A  Spirit  Level. — Take  out  the  screws  which 
hold  it  on  the  plate,  pull  ofi*  the  brass  ends  of  the  tube,  and 
with  a  knife  blade  scrape  out  the  plaster  from  the  tube;  then 
with  a  stick  made  a  little  smaller  than  the  diameter  of  the 
tube,  and  with  its  end  hollowed  out,  so  that  it  will  beair  only 
on  the  broad  surface  of  the  level  vial,  push  out  the  old  vial 
and  replace  it  with  a  new  one,  taking  care  that  the  crowning 
side,  which  is  usually  marked  with  a  file  on  the  end  of  the  vial, 
is  placed  on  the  upper  side. 

When  the  vial  does  not  fit  the  tube  it  must  be  wedged  up 
by  putting  under  little  slips  of  paper  until  it  moves  in  snugly. 

After  the  vial  is  in  its  place,  put  around  its  ends  a  little 
boiled  plaster,  mixed  with  water  to  the  consistency  of  putty, 
taking  care  not  to  allow  any  to  cover  the  little  tip  of  the 
glass,  then  slip  in  the  brass  ends  and  the  operation  will  be 
completed. 

A  little  beeswax,  melted  and  dropped  upon  the  ends  of  the 
vial,  is  equally  as  good  as  the  boiled  plaster,  and  often  more 
easily  obtained. 

We  would  here  remark  that  an  extra  glass  and  level  viala 
are  always  furnished,  free  of  charge,  with  our  instruments, 
whenever  desired  by  the  purchaser. 

Sizes  of  the  Plain  Compass, 
Three  different  sizes  of  this  instrument  are  in  common  use, 
having  respectively  four,  five  and  six-inch  needles,  and  dif- 
fering also  in  the  length  cf  the  main  plate,  which  in  the  four 


22 


THE  PLAIN  COMPASS. 


inch  compass  is  twelve  and  a  half  inches  long,  and  in  the 
larger  sizes,  fifteen  and  a  half  inches. 

The  six-inch  needle  compass  is  generally  preferred. 

Weight  of  the  Plain  Compasses. 

The  average  weights  of  the  different  sizes,  with  the  brass 

mountings  of  the  Jacob  staff,  are  : 

For  the  4-mch  needle,  6  lbs. 
For  the  5-inch  needle,  7^  lbs. 
For  the  6-inch  needle,  8^  lbs. 

The  plain  compass,  which  was  the  only  one  in  use  in  this 
country  previous  to  the  time  of  David  Rittenhouse,  has  grad- 
ually e^iven  way  to  the  superior  advantages  of  thfi  Vernier  ol 
Rittenhouse  compass,  which  we  shall  now  proceed  to  describe 


THE  VERNIER  COMPASS. 


23 


Surveying  Instruments. 


THE  VERNIER  COMPASS. 

Tliis  instrument,  represented  in  the  engraving  opposite,  is  in 
most  respects  like  that  already  described,  differing  from  it 
mainly  in  having  its  compass  circle,  to  which  is  attached  a 

vernier,''  movable  about  a  common  centre  a  short  distance 
in  either  direction,  thus  enabling  the  surveyor  to  set  the  zeros 
of  the  circle  at  any  required  angle  with  the  line  of  sights, 
the  number  of  degrees  contained  in  this  angle  or  the  varia- 
tion of  the  needle  "  being  read  off  by  the  vernier. 

The  movement  of  the  circle  is  effected  either  by  a  slow 
moving  or  tangent  screw,"  as  shown  in  the  engraving,  or  by 
a  concealed  rack  and  pinion — the  head  of  which  projects  from 
the  under  side  of  the  main  compass  plate. 

When  the  variation  is  set  off  as  described,  the  circle  is  se- 
curely fastened  in  its  position  by  a  clamping  nut  underneath 
the  main  plate. 

Ball  Spindle. — The  compass  is  usually  fitted  to  a  spindle 
made  slightly  conical  and  having  on  its  lower  end  a  ball  turned 
perfectly  spherical,  and  confined  in  a  socket  by  a  pressure  so 
light  that  the  ball  can  be  moved  in  any  direction  in  the  opera- 
tion of  leveling  the  compass. 

The  ball  is  placed  either  in  the  brass  head  of  the  Jacob 
Staff  already  shown  with  the  previous  instrument,  or  still 
better,  in  the  compass  tripod  seen  in  the  engraving  of  the 
Vernier  Transit  beyond. 

The  superiority  of  the  vernier  over  the  plain  compass  con* 


24 


THE  VERNIER  COMPASS. 


Bists  in  its  adaptation  to  the  retracing  the  lines  of  an  old 
surve}^  and  to  the  surveys  of  the  U.  S  public  lands,  where 
the  lines  are  based  on  a  true  meridian. 

Variation  of  the  Needle, 

It  is  well  known  that  the  magnetic  needle,  in  almost  all 
parts  of  the  United  States,  points  more  or  less  to  the  east  or 
west  of  a  true  meridian,  or  north  and  south  line. 

This  deviation,  which  is  called  the  variation  or  declination 
of  the  needle,  is  not  constant,  but  increases  or  decreases  to 
a  very  sensible  amount  in  a  series  of  years. 

Thus  at  Troy.  N,  Y.,  a  line  bearing  in  1838^  N.  31^  E., 
would  now,  1870,  with  the  same  needle,  have  a  bearing  of 
about  N.  32^  E.,  the  needle  having  thus  in  that  interval 
travelled  a  full  degree  to  the  west. 

For  this  reason,  therefore,  in  running  over  the  lines  of  a 
farm  from  field  notes  of  some  years  standing,  the  surveyor 
would  be  obliged  to  make  an  allowance,  both  perplexing  and 
uncertain,  in  the  bearing  of  every  line. 

To  avoid  this  difficulty  the  vernier  was  devised,  the  arrange- 
ment of  which  we  shall  now  describe. 

The  Vernier  is  divided  on  its  edge  to  thirty  equal  parts, 
and  figured  in  two  series  on  each  side  of  the  centre  line. 

In  the  same  plane  with  the  vernier  is  an  arc  or  limb^  fixed 
to  the  main  plate  of  the  compass,  and  graduated  to  half 
degrees. 

The  surfaces  of  both  vernier  and  limb  are  silvered. 

On  the  vernier  are  thirty  equal  divisions,  which  exactly 
correspond  in  length  with  thirty-one  of  the  half  degrees  of 
the  limb. 

Each  division  of  the  vernier  is,  therefore,  one-thirtieth  or, 
in  other  words,  one  minute  longer  than  a  single  division  of 
the  limb. 

To  Read  the  Vernier. — In  "reading the  vernier,  if  it  is 


THE  VERNIER  COMPASS. 


25 


moved  to  the  right,  count  the  minutes  from  its  zero  point  to 
the  left,  and  vice  versa.  Proceed  thus  until  a  division  on 
the  vernier  is  found  exactly  in  line  with  another  on  the  limb, 
and  the  lower  row  of  figures  on  the  vernier  will  give  the 
number  of  minutes  passed  over.  When  the  vernier  is  moved 
more  than  fifteen  minutes  to  either  side  the  number  of  the 
additional  minutes  up  to  thirty  or  one-half  degree  of  the  limb 
is  given  by  the  upper  row  of  figures  on  the  opposite  side  of 
the  vernier. 

To  read  beyond  thirty,  add  the  minutes  given  by  the  ver- 
nier to  that  number,  and  the  sum  will  be  the  correct  reading. 

In  all  cases  when  the  zero  point  of  the  vernier  passes 
a  whole  degree  of  the  limb,  this  must  be  added  to  the  minutes, 
in  order  to  define  the  distance  over  which  the  vernier  has 
been  moved. 

To  Turn  off  the  Variation. — It  will  now  be  seen  that  the 
surveyor  having  the  vernier  compass,  can  by  moving  the 
vernier  to  either  side,  and  with  it  of  course  the  compass  cir- 
cle attached,  set  the  compass  to  any  variation. 

He  therefore  places  his  instrument  on  some  well  defined 
line  of  the  old  survey,  and  turns  the  tangent  screw  until  the 
needle  of  his  compass  indicates  the  same  bearing  as  that 
given  in  the  old  field  notes  of  the  original  survey. 

Then  screwing  up  the  clamping  nut  underneath  the  ver- 
nier, he  can  run  all  the  other  lines  from  the  old  field  notes 
without  further  alteration. 

The  reading  of  the  vernier  on  the  limb  in  such  a  case  would 
give  the  change  of  variation  at  the  two  dififerent  periods. 

The  variation  of  the  needle  at  any  place  being  known,  a 
true  meridian,  or  north  and  south  line,  may  be  run  by  moving 
the  vernier  to  either  side,  as  the  variation  is  east  or  west, 
until  the  arc  passed  over  on  the  limb  is  equal  to  the  angle  of 
variation;  and  then  turning  the  compass  until  the  needle  is 
made  to  cut  the  zeros  on  the  divided  circle,  when  the  line  of 


26 


THE  VERNIER  COMPASS. 


the  sights  would  give  the  direction  of  the  true  meridian  of 
the  place. 

Such  a  change  in  the  position  of  the  vernier  is  necessary 
in  surveying  the  U.  S.  public  lands,  which  are  always  run 
from  the  true  meridian. 

The  line  of  no  variation,  as  it  is  called,  or  that  upon 
which  the  needle  will  indicate  a  true  north  and  south  direc- 
tion, is  situated  in  the  United  States,  nearly  in  an  imaginary 
line  drawn  from  the  middle  of  lake  Erie  to  Cape  Hatteras, 
on  the  coast  of  North  Carolina. 

A  compass  needle,  therefore,  placed  east  of  this  line  would 
have  a  variation  to  the  west,  and  when  placed  west  of  the 
line,  the  variation  would  be  to  the  east,  and  in  both  cases 
the  variation  would  increase  as  the  needle  was  carried  far- 
ther from  the  line  of  no  variation. 

Thus  in  Minnesota  the  variation  is  from  15^  to  16®  to  the 
east,  while  in  Maine  it  is  from  17®  to  18®  to  the  west. 

At  Troy,  in  the  present  year,  18*70,  the  variation  is  about 
9®  to  the  west,  and  is  increasing  in  the  same  direction  from 
two  to  three  minutes  annually. 

To  Read  to  Minutes. — A  less  important  use  of  the  vernier 
is  to  give  a  reading  of  the  needle  to  single  minutes,  which  is 
obtained  as  follows: 

First  be  sure,  as  in  all  observations,  that  the  zero  of  the 
vernier  exactly  corresponds  with  that  of  the  limb  ;  then 
noting  the  number  of  whole  degrees  given  by  the  needle, 
move  back  the  compass  circle  with  the  tangent  screw  until 
the  nearest  whole  degree  mark  is  made  to  coincide  with  the 
point  of  the  needle,  read  the  vernier  as  before  described,  and 
this  reading  added  to  the  whole  degrees  will  give  the  bearing 
to  minutes. 

To  use  the  Vernier  Compass, 
Proceed  in  the  same  manner  as  directed  in  regard  to  the 
Plain  Compass,  when  making  new  surveys,  always  taking 


THE  VERNIER  COMPASS. 


27 


care  that  the  vernier  is  set  at  zero  and  securely  clamped  by 
screwing  up  the  nut  beneath  the  plate. 

In  surveying  old  farms,  allowance  and  correction  must  be 
made  for  the  variation,  as  just  described. 

Sizes  of  the  Vernier  Compass, 
We  make  three  sizes  of  this  compass,  having  needles  of  four, 
five  and  six  inches  long  respectively,  the  main  plates  of  the 
two  largest  being  over  fifteen  inches  long ;  and  of  the  smallest 
size,  thirteen  inches,  the  sights  of  the  last  are  also  about  an 
inch  shorter. 

In  the  four  and  five  inch  Vernier  Compasses,  the  variation 
arc  is  within  the  compass  circle  like  that  of  the  ra-ilroad  com- 
pass hereafter  described,  and  the  variation  is  set  off  to  min- 
utes by  a  pinion  head  underneath  the  plate ;  the  circle  is  also 
•clamped  at  any  variation  by  a  screw  placed  opposite  the  pinion. 

Weight  of  the  Vernier  Compasses. 
The  average  weights  of  the  different  sizes,  including  the 
brass  head  of  the  Jacob  Staff,  beginning  with  the  smallest, 
are  respectively  5|,  7  J  and  9^  pounds. 


28 


THE  VERNIER  TRANSIT. 


Surveying  Instruments. 


THE  VERNIEE  TRANSIT. 

This  instrument,  shown  in  the  engraving  opposite,  resembles 
the  Vernier  Compass  in  its  construction  and  general  principles, 
differing  from  it  mainly  in  the  use  of  a  telescope  in  place  of  ihf^ 
ordinary  sights.  The  variation  of  the  needle  is  set  off  by  a 
pinion,  as  shown,  and  the  circle  clamped  by  a  nut  underneath 
the  plate  as  usual. 

The  instrument  is  clamped  to  the  spindle  and  secured  from 
falling  from  it  by  the  clamp  screw  and  spring  catch,  seen  on 
opposite  sides  of  the  socket  in  the  engraving. 

The  Vernier  Transit  should  always  be  used  with  the  com- 
pass tripod  at  least,  as  shown  in  the  engraving,  and  often,  es- 
pecially when  furnished  with  the  extra  attachments  to  tele- 
scope, is  placed  upon  the  light  leveling  tripod,  shown  with  the 
Surveyor's  Transit  beyond,  and  described  in  our  account  of 
that  instrument. 

The  needle  of  this  instrument  is  either  four,  five  or  six 
inches  long,  as  the  surveyor  may  prefer,  the  one  with  the  six 
inch  needle  being  shown  in  the  engraving,  and  generally 
selected  by  our  customers. 

The  advantages  of  the  Vernier  Transit  over  the  ordinary 
compass,  are  due  mainly  to  the  telescope  and  its  attachments, 
which  we  ehall  proceed  to  describe  in  detail. 


EENJ  D.  B-H:NS-OTf.  N.  Y. 


THE  VERNIER  TRANSIT.  29 


The  telescope  is  from  ten  to  twelve  inch- 
es long,  and  sufficiently  powerful  to  see 
and  set  a  flag  at  a  distance  of  two  miles  in 
a  clear  day. 

The  cross-bar  in  which  it  is  fixed,  turna 
readily  in  the  standards,  so  that  the  tele- 
s' scope  can  be  turned  in  either  direction,  and 
back  and  fore  sights  be  taken  without  re- 
moving the  instrument. 

Like  all  telescopes  used  by  us  in  our  in- 
struments, it  shows  objects  in  an  erect 
position. 

The  Telescope. — The  interior  construc- 
tion  of  the  telescope  of  the  Vernier  Transit, 
\  which  is  very  similar  to  those  of  the  other 
/  instruments  we  shall  describe,  is  well 
shown  in  the  longitudinal  section  represen- 
B    ted  in  fig.  4. 

As  here  seen,  the  telescope  consists  es- 
sentially of  an  object-glass,  an  eye-piece 
tube,  and  a  cross-wire  ring  or  diaphragm. 

The  object-glass  is  composed  of  two 
lenses,  one  of  flint,  the  other  of  crown 
glass,  which  are  so  made  and  disposed  as 
to  show  the  object  seen  through  it  without 
color  or  distortion. 

The  object  glass  and  the  whole  telescope 
is  therefore  said  to  be  "  achromatic." 

The  eye-piece  is  made  up  of  four  plano- 
convex lenses,  which,  beginning  at  the  eye 
end,  and  proceeding  on,  are  called  respec- 
tively, the  eye,  the  field,  the  amplifying, 
and  the  object  lenses. 


30 


THE  VERNIER  TRANSIT. 


Together,  they  form  a  compound  microscope,  magnifying 
the  minute  image  of  any  object  formed  at  the  cross-wires  by 
the  interposition  of  the  object  glass. 


Fig.  5. 

The  Cross  Wires. — The  cross-wire  diaphragm,  two  views 
of  which  are  here  exhibited,  is  a  small  ring  of  brass,  sus- 
pended in  the  tube  of  the  telescope  by  four  capstan  head 
screws,  which  press  upon  the  washers  shown  on  the  outside 
of  the  tube. 

The  ring  can  thus  be  moved  in  either  direction  by  working 
the  screws  with  an  ordinary  adjusting  pin. 

Across  the  flat  surface  of  the  ring  two  fine  fibres  of  spi- 
der's web  are  extended  at  right  angles  to  each  other,  their 
ends  being  cemented  with  beeswax  or  varnish,  into  fine  linea 
cut  in  the  metal  of  the  ring. 

The  intersection  of  the  wires  forms  a  very  minute  point, 
which,  when  they  are  adjusted,  determines  the  optical  axis 
of  the  telescope,  and  enables  the  surveyor  to  fix  it  upon  an 
object  with  the  greatest  precision. 

The  imaginary  line  passing  through  the  optical  axis  of  the 
telescope,  is  termed  the  *'line  of  collimation,"  and  the  opera- 
tion of  bringing  the  intersection  of  the  wires  into  the  optical 


THE  VERNIER  TRANSIT. 


31 


axis,  is  called  the    adjustment  of  the  line  of  collimation/' 
This  will  be  hereafter  described. 

The  openings  in  the  telescope  tube  are  made  considerably 
larger  than  the  screws,  so  that  when  these  are  loosened,  the 
whole  ring  can  be  turned  around  for  a  short  distance  in  either 
direction. 

The  object  of  this  will  be  seen  more  plainl}^,  when  we  de- 
scribe the  means  by  which  the  wire  is  made  truly  vertical. 

The  sectional  view  of  the  telescope  (fig.  4)  also  shows  two 
moveable  rings,  one  placed  at  A  A,  the  other  at  0  C,  which 
are  respectively  used,  to  effect  the  centering  of  the  eye-piece, 
and  the  adjustment  of  the  object-glass  slide. 

The  centering  of  the  eye-tube  is  performed  after  the  wires 
have  been  adjusted,  and  is  effected  by  moving  the  ring,  by 
means  of  the  screws,,  shown  on  the  outside  of  the  tube,  until 
the  intersection  of  the  wires  is  brought  into  the  centre  of  the 
field  of  view. 

The  adjustment  of  the  object  slide,  which  will  be  fully  de- 
scribed in  our  account  of  the  Leveling  Instrument,  secures 
the  movement  of  the  object-glass  in  a  straight  line,  and  thus 
keeps  the  line  of  collimation  in  adjustment  through  the  whole 
range  of  the  slide,  preventing  at  the  same  time  what  is  term- 
ed the  ''travelling''  of  the  wires. 

This  adjustment,  which  is  peculiar  to  our  telescopes,  is  . 
always  made  in  the  process  of  construction,  and  needing  no 
further  attention  at  the  hands  of  the  engineer,  is  concealed 
within  the  hollow  ball  of  the  telescope  axis. 

Optical  Principles  of  the  Telescope. 

In  order  that  the  advantages  gained  by  the  use  of  the  tele 
scope  may  be  more  fully  understood,  we  shall  here  venture 
briefly  to  consider  the  optical  principles  involved  in  its  coia* 
struction. 


32 


THE  VERNIER  TRANSIT. 


We  are  said  to  "  see objects  because  the  rays  of  light 
which  proceed  from  all  their  parts,  after  passing  through  the 
pupil  of  the  eye,  are  by  the  crystalline  lens  and  vitreous 
humor,  converged  to  a  focus  on  the  retina,  where  they  form 
a  very  minute  inverted  image;  an  impression  of  which  is 
conveyed  to  the  brain  by  the  optic  nerve. 

The  rays  proceeding  from  the  extremities  of  an  object,  and 
crossing  at  the  optic  center  of  th6  eye,  form  the  visual 
angle,''  or  that  under  which  the  object  is  seen. 

The  apparent  magnitude  of  objects  depends  on  the  size  of 
the  visual  angle  which  they  subtend,  and  this  being  great  or 
small,  as  the  object  is  near  or  distant — the  objects  will  ap- 
pear large  or  small,  in  an  inverse  proportion  to  the  distances 
which  separate  them  from  the  observer. 


be  twice  that  observed  at  B.  If,  therefore,  the  visual  angle 
subtended  by  any  object,  can  be  made  by  any  means  twice 
as  large,  the  same  effect  will  be  produced  as  if  the  observer 
were  moved  up  over  one  half  the  intervening  distance. 

Now  this  is  the  principal  advantage  gained  in  the  use  of 
a  telescope. 

The  object-glass  receiving  the  rays  of  light  which  proceed 
from  all  the  points  of  a  visible  object,  converges  them  to  a 
focus  at  the  cross-wires,  and  there  forms  a  minute,  inverted, 
and  very  bright  image,  which  may  be  seen  by  placing  a  piece 
of  ground  glass  to  receive  it  at  that  point. 

The  eye-piece  acting  as  a  compound  microscope,  magnifies 


Fig.  6. 


Thus,  (in  fig.  6,)  if  the 
distance  0  A  is  one-half 
of  0  B,  the  visual  angle, 
subtended  by  the  object 
at  the  point  A,  and  there- 
fore the  apparent  mag- 
nitude of  the  object  will 


THE  VERNIER  TRANSIT. 


33 


this  image,  restores  it  to  its  natural  position,  and 
conveys  it  to  the  eye. 

The  visual  angle  vi^hich  the  image  there  sub- 
tends, is  as  many  times  greater  than  that  which 
would  be  formed  without  the  use  of  the  telescope, 
as  the  number  which  expresses  its  magnifying 
power.  ,y 

Thus,  a  telescopa^;>^hicii  magnifies  twenty 
times,  increases  the  visual  angle  just  as  much, 
and  therefore  diminishes  the  apparent  distance  of 
the  object  twenty  times — or  in  other  words,  it 
will  show  an  object  two  hundred  feet  distant, 
with  the  same  distinctness  as  if  it  was  distant 
only  ten  feet  from  the  naked  eye. 

The  accompanying  cut,  (fig.  1)  which  we  are 
kindly  permitted  to  copy  from  an  excellent  trea- 
^  tise  on  surveying,  by  Prof.  Gillespie  of  Union 
1^  College,  will  give  a  correct  idea  of  the  manner 
in  which  the  rays  of  light  coming  from  an  object 
are  affected,  by  passing  through  the  several 
glasses  of  a  telescope. 

We  shall  only  consider  the  rays  which  proceed 
from  the  extremities;  these,  after  passing  through* 
the  object-glass,  here  shown  as  a  single  lens,  are 
conveyed  to  the  point  B,  the  centre  of  the  cross- 
wires  and  the  common  focus  of  the  object  and 
eye-glasses.  At  this  place  the  rays  cross  each 
other  and  the  image  is  inverted. 

The  rays  next  come  to  the  object  lens  C,  and 
passing  through  it  are  refracted  so  as  again  to 
cross  each  other,  and  come  thus  to  the  amplifying 
lens  D.  By  this  they  are  again  refracted,  made 
more  nearly  parallel,  and  thus  reach  the  large 
field  lens  E.    After  passing  through  this,  they 


34 


THE  VERNIER  TRANSIT. 


form  a  magnified  and  erect  image  in  the  focus  of  the  eyt 
lens  G.  By  the  eye  lens  the  image  is  still  further  magnified, 
and  at  last  enters  the  eye  of  the  observer,  subtending  an 
angle  as  much  greater  than  that  at  the. point  0,  as  is  the 
magnifying  power  of  the  telescope. 

In  place  of  the  eye-piece  of  four  lenses,  which  we  have 
just  been  considering,  and  which  is  exclusively  used  in  all 
American  instruments  made  at  the  present  day;  another, 
which  has  but  three  lenses,  is  often  seen  in  the  telescopes  of 
imported  instruments. 

This  latter,  which  inverts  the  object,  though  saving  a  little 
more  light  than  the  former,  is  exceedingly  troublesome  t-o 
the  inexperienced  observer,  and  has  never  been  popular  in 
American  engineering. 

To  ascertain  the  Magnifying  Power  of  a  Telescope, 

Set  up  the  instrument  about  twenty  or  thirty  feet  from  the 
Bide  of  a  white  wooden  house,  and  observe  through  the  tele- 
scope the  space  covered  by  one  of  the  boards  in  the  field  of 
the  glass;  then  still  keeping  that  eye  on  the  telescope,  hold 
open  the  other  with  the  finger,  if  necessary,  and  look  with  it 
at  the  same  object.  By  steady  and  careful  observation  there 
will  appear  on  the  surface  of  the  magnified  board,  a  number 
of  smaller  ones  seen  by  the  naked  eye,  count  these,  and  we 
shall  obtain  the  magnifying  power. 

If  the  limits  of  the  magnified  board,  as  seen  through  the 
telescope,  can  be  noted  so  as  to  be  remembered  after  the  eye 
is  removed,  the  number  of  boards  contained  in  this  space 
may  then  be  easily  counted. 

The  side  of  an  unpainted  brick  wall,  or  any  other  surface 
containing  a  number  of  small,  well  marked  and  equal  objects, 
may  be  observed,  in  place  of  the  surface  we  have  described 

The  operation  described  requires  great  care  and  close. 


THE  VERNIER  TRANSIT. 


35 


observation,  but  raay  be  performed  with  facility  after  a  little 
practice. 

We  have  spoken  of  the  effect  of  the  telescope  in  magnify- 
ing objects,  but  have  not  mentioned  vrhat  is  termed  its 
illuminating  power/' 

This  arises  from  the  great  diameter  or  aperture  of  the 
object-glass  compared  with  that  of  the  pupil  of  the  eye,  which 
enables  the  observer  to  intercept  many,  more  rays  of  light, 
and  bring  the  object  to  the  eye  highly  illuminated. 

The  advantage  gained  in  this  increase  of  light,depends,  as 
is  evident,  on  the  size  of  the  object  glass,  and  the  perfection 
with  which  the  lenses  transmit  the  light  without  absorbing 
or  reflecting  it. 

The  superficial  magnifying  power  of  a  telescope,  is  found 
by  squaring  the  number  which  expresses  its  linear  magnify- 
ing power;  thus  a  telescope  which  magnifies  twenty  times, 
increases  the  surface  of  an  object  four  hundred  times. 

Before  an  observation  is  made  with  the  telescope,  the  eye- 
piece should  be  moved  in  or  out,  until  the  wires  appear  dis- 
tinct to  the  eye  of  the  operator;  the  object-glass  is  then  ad- 
justed by  turning  the  pinion  head  until  the  object  is  seen  clear 
and  well  defined,  and  the  wires  appear  as  if  fastened  to  its 
surface. 

The  intersection  of  the  wires,  being  the  means  by  which 
the  optical  axis  of  the  telescope  is  defined,  should  be  brought 
precisely  upon  the  centre  of  the  object  to  which  the  instru- 
ment is  directed. 

Having  thus  briefly  considered  the  principles,  we  shall  now 
proceed  to  describe  the 

Attachments  of  the  Telescope, 
A  telescope  is  said  to  be  "  plain when  it  is  without  any 
appendages  to  its  tube  or  axis,  as  that  of  the  Engineer's 


36 


THE  VERNIER  TRANSIT. 


Transit  shown  in  the  engraving,  and  most  instruments  are 
made  in  that  manner. 

Many  surveyors,  however,  prefer  to  add  these  conveniences, 
and  we  shall  now  consider  them  in  detail. 

Clamp  and  Tangent. — This  consists  essentially  of  a  ring, 
encircling  the  axis  of  the  telescope,  and  having  two  project- 
ing arms,  the  one  above  being  slit  through  the  middle  and 
holding  the  clamp  screw,  the  other  much  longer  and  below, 
is  connected  with  the  tangent  screw. 

As  soon  as  the  clamp  screw  is  tightened,  the  ring  is  brought 
firmly  around  the  axis,  and  the  telescope  can  then  be  moved 
up  or  down  by  turning  the  tangent  screw. 

The  clamp  and  tangent  ought  always  to  accompany  the 
vertical  circle,  and  the  level  on  the  telescope. 

Vertical  Circle. — A  divided  circle  as  seen  in  the  cut  of  the 
Vernier  Transit,  is  often  attached  to  the  axis  of  the  telescope, 
giving,  with  a  vernier,  the  means  of  measuring  vertical  an- 
gles with  great  facility. 

We  make  two  sizes  of  these  circles,  one  of  about  3|  inches 
diameter,  seen  with  this  instrument,  the  other  an  inch  larger, 
and  shown  in  the  cut  of  the  Surveyor's  Transit.  The  former 
is  graduated  to  single  degrees,  and  reads  by  the  vernier,  to 
five  minutes  of  a  degree.  The  latter,  divided  to  half  degrees, 
gives  a  reading,  with  the  vernier,  to  single  minutes. 

The  vertical  circle  is  fitted  firmly  to  the  telescope  axis,  and 
fastened  with  a  screw,  so  that  it  remains  permanent. 

The  vernier,  however,  may  be  shifted  in  either  direction, 
by  loosening  the  screws  which  confine  it  to  the  standards. 

The  vernier  of  the  small  circle  is  divided  into  twelve  equal 
parts,  which  correspond  with  thirteen  degrees  on  the  circle. 

Each  division  of  the  vernier  is,  therefore,  one-twelfth  of 
one  degree,  or  five  minutes  longer  than  a  single  division  of 
the  circle,  so  that  the  angles  are  read  to  five  minutes  of  a 
degree. 


THE  VERNIER  TRANSIT. 


37 


The  vernier  is  double,  having  its  zero  point  in  the  middle, 
and  the  reading*  up  to  thirty  minutes,  is  said  to  be  direct; 
thai  is,  if  the  circle  is  moved  to  the  right,  the  minutes  are 
read  off  on  the  right  side  of  the  vernier,  and  vice  versa. 

The  minutes  beyond  thirty  are  obtained  on  the  opposite 
side,  and  in  the  lower  row  of  figures. 

By  following  these  directions,  and  noticing  the  first  divi- 
sions on  the  circle  and  vernier,  which  exactly  correspond,  the 
surveyor  can  obtain  a  reading  to  five  minutes  with  great 
facility. 

Level  on  Telescope. — Besides  the  vertical  circle,  there  is 
sometimes  a  small  level  attached  to  the  telescope  of  this  and 
other  instruments,  which  we  shall  hereafter  describe. 

Such  an  attachment  is  shown  in  the  cut  of  the  Surveyor's 
Transit,  and  its  adjustment  and  advantages  will  be  explain- 
ed in  our  account  of  that  instrument. 

Sights  on  Telescope. — We  are  sometimes  desired  by  sur- 
veyors to  place  a  pair  of  short  sights  on  the  upper  side  of 
the  telescope  tube. 

They  are  best  made  to  fold  close  to  the  tube  when  not  in 
use,  like  those  of  the  pocket  compass,  described  hereafter. 

These  sights  are  useful  in  taking  back  sights  without 
turning  the  telescope,  and  in  sighting  through  bushes  or  in 
the  forest,  and  as  the  telescope  can  be  turned  up  or  down, 
answer  all  the  purposes  of  the  longer  sights  of  the  ordinary 
compass. 

Sights  for  Right  Angles. — Besides  the  sights  just  men- 
tioned, we  have  often  attached  others  to  the  plate  of  the 
instrument,  on  either  side  of  the  compass  circle  or  on  the 
standards. 

These  being  adjusted  to  the  telescope  give  a  very  ready 
means  of  laying  off  right  angles,  or  running  out  offsets,  with 
out  changing  the  position  of  the  instrument 


38 


THE  VERNIER  TRANSIT. 


To  adjust  the  Vernier  Transit. 

The  Levels  of  this  instrument  have  a  capstan  head  screw 
at  each  end,  and  are  adjusted  with  a  steel  pin  in  the  same 
manner  as  those  of  the  Plain  compass. 

The  Needle  is  also  adjusted  as  described  in  our  account  of 
that  instrument. 

Line  of  Collimation. — To  make  this  adjustment,  which  is, 
in  other  words,  to  bring  the  intersection  of  the  wires  into 
the  optical  axis  of  the  telescope,  so  that  the  instrument, 
when  placed  in  the  middle  of  a  straight  line  will,  by  the 
revolution  of  the  telescope,  cut  its  extremities — proceed  as 
follows: 

Set  the  instrument  firmly  on  the  ground  and  level  it  care- 
fully; and  then  having  brought  the  wires  into  the  focus  of 
the  eye-piece,  adjust  the  object-glass  on  some  well  defined 
point,  as  the  edge  of  a  chimney  or  other  object,  at  a  distance 
of  from  two  to  five  hundred  feet;  determine  if  the  vertical  wire 
is  plumb,  by  clamping  the  instrument  firmly  to  the  spindle  and 
applying  the  wire  to  the  vertical  edge  of  a  building,  or  ob- 
serving if  it  will  move  parallel  to  a  point  taken  a  little  to 
one  side;  should  any  deviation  be  manifested,  loosen  the 
cross-wire  screws,  and  by  the  pressure  of  the  hand  on  the 
head  outside  the  tube,  move  the  ring  around  until  the  error 
is  corrected. 

The  wires  being  thus  made  respectively  horizontal  and 
vertical,  fix  their  point  of  intersection  on  the  object  selected  ; 
clamp  the  instrument  to  the  spindle,  and  having  revolved  the 
telescope,  find  or  place  some  good  object  in  the  opposite 
direction,  and  at  about  the  same  distance  from  the  instrument 
as  the  first  object  assumed. 

Great  care  should  always  be  taken  in  turning  the  telescope, 
that  the  position  of  the  instrument  upon  the  spindle  is  not  iu 
tlie  slightest  degree  disturbed. 


THB  VERNIER  TRANSIT. 


39 


Now,  having  found  or  placed  an  object  which  the  vertical 
wire  bisects,  unclamp  the  instrument,  turn  it  half  way  around^ 
and  direct  the  telescope  to  the  first  object  selected;  having 
bisected  this  with  the  wires,  again  clamp  the  instrument, 
revolve  the  telescope,  and  note  if  .the  vertical  wire  bisects 
the  second  object  observed. 

Should  this  happen,  it  will  indicate  that  the  wires  are  in 
adjustment,  and  the  points  bisected  are  with  the  centre  of 
the  instrument,  in  the  same  straight  line. 

If  not,  however,  the  space  which  separates  the  wires  from 
the  second  point  observed,  will  be  double  the  deviation  of 
that  point  from  a  true  straight  line,  which  may  be  conceived 
as  drawn  through  the  first  point  and  the  centre  of  the  instru- 
ment, since  the  error  is  the  result  of  two  observations,  made 
with  the  wires  when  they  are  out  of  the  optical  axis  of  the 
telescope. 

Fig.  8. 


For  as  in  the  diagram,  let  A  represent  the  centre  of  the 
instrument,  and  B  C  the  imaginary  straight  line,  upon  the 
extremities  of  which  the  line  of  collimation  is  to  be  adjusted. 

B  represents  the  object  first  selected,  and  D  the  point 
which  the  wires  bisected,  when  the  telescope  was  made  to 
revolve. 

When  the  instrument  is  turned  half  around,  and  the  tele- 
scope again  directed  to  B,  and  once  more  revolved,  the  wires 
will  bisect  an  object,  E,  situated  as  far  to  one  side  of  the  true 
line  as  the  point  D  is  on  the  other  side. 

The  space,  D  E,  is  therefore  the  sum  of  two  deviations  of 
the  wires  frcm  a  true  straight  line,  and  the  error  is  mada 
very  appareht 


40 


THE  VERNIER  TRANSIT, 


In  order  to  correct  it,  use  the  two  capstan  Lead  screws  on 
the  sides  of  the  telescope,  these  being  the  ones  which  affect 
the  position  of  the  vertical  wire. 

Remember  that  the  eye-piece  inverts  the  position  of  the 
wires,  and  therefore  that  in  loosening  one  of  the  screws  and 
tightening  the  other  on  the  opposite  side,  the  operator  must 
proceed  as  if  to  increase  the  error  observed.  Having  in  this 
manner  moved  back  the  vertical  wire  until,  by  estimation, 
one-quarter  of  the  space,  D  E,  has  been  passed  over,  return 
the  instrument  to  the  point  B,  revolve  the  telescope,  and  if 
the  correction  has  been  carefully  made,  the  wires  will  now 
bisect  a  point,  C,  situated  midway  between  D  and  E,  and  in 
the  prolongation  of  the  imaginary  line,  passing  through  the 
point  B  and  the  centre  of  the  instrument. 

To  ascertain  if  such  is  the  case,  turn  the  instrument  half 
around,  fix  the  telescope  upon  B,  clamp  to  the  spindle,  and 
again  revolve  the  telescope  towards  0.  If  the  wires  again 
bisect  it,  it  will  prove  that  they  are  in  adjustment,  and  that 
the  points,  B,  A,  C,  all  lie  in  the  same  straight  line. 

Should  the  vertical  wire  strike  to  one  side  of  C,  the  error 
must  be  corrected  precisely  as  above  described,  until  it  is 
entirely  removed. 

Another  method  of  adjusting  the  line  of  collimation  often 
employed  in  situations  where  no  good  points  in  opposite 
directions  can  be  selected  upon  which  to  reverse  the  wires, 
may  here  be  described. 

The  operator  sets  up  the  instrument  in  some  position 
which  commands  a  long  sight  in  the  same  direction,  and 
having  leveled  his  instrument,  clamps  to  the  spindle,  and 
with  the  telescope  locates  three  points  which  we  will  term  A, 
B  and  C,  which  are  distant  from  the  instrument  about  one, 
two  and  three  hundred  feet  respectively. 

These  points,  which  are  usually  determined  by  driving  a 
nail  into  a  wooden  stake  set  firmly  into  the  ground,  will  all 


THE  VERNIER  TRANSIT. 


41 


lie  in  the  same  straight  line,  however  much  the  wires  are  out 
of  adjustment,  since  the  position  of  the  instrument  remains 
unchanged  during  the  whole  operation. 

Having  fixed  these  points  he  now  moves  the  instrument  to 
B,  and  sets  its  centre  directly  over  the  nail  head,  by  letting 
down  upon  it  the  point  of  a  plumb-bob  suspended  from  the 
tripod. 

Then  having  leveled  the  instrument,  he  directs  the  wires 
to  A,  clamps  to  the  spindle  and  revolves  the  telescope 
towards  C.  Should  the  wires  strike  the  nail  at  that  point, 
it  would  show  that  they  were  in  adjustment. 

Should  any  deviation  be  observed,  the  operator  must  cor- 
rect it  by  moving  the  wire  with  the  screws  until,  by  estima- 
tion, half  the  error  is  removed. 

Then  bringing  the  telescope  again  upon  either  A  or  C,  and 
revolving  it,  he  will  find  that  the  wires  will  strike  the  point 
in  the  opposite  direction  if  the  proper  correction  has  been 
applied. 

If  not,  repeat  the  operation  until  the  telescope  will  exactly 
cut  the  two  opposite  points,  when  the  intersection  of  the 
wires  will  be  in  the  optical  axis,  and  the  line  of  collimation 
in  adjustment. 

In  our  description  of  the  previous  operation,  we  have 
spoken  more  particularly  of  the  vertical  wire,  because  in  a 
revolving  telescope  this  occupies  the  most  important  place, 
the  horizontal  one  being  employed  mainly  to  define  the  cen- 
tre of  the  vertical  wire,  so  that  it  may  be  moved  either  up  or 
down  without  materially  disturbing  the  line  of  collimation. 

The  wires  being  adjusted,  their  intersection  may  now  be 
brought  into  the  centre  of  the  field  of  view. 

The  Eye-Piece  is  centered  by  moving  the  screws  A  A, 
shown  in  the  sectional  view  of  the  telescope.  Fig.  4,  which  are 
slackened  and  tightened  in  pairs,  the  movement  being  now 
direct,  until  the  wires  are  seen  in  their  proper  position. 


42 


THE  VEIINIER  TRANSIT. 


It  is  here  proper  to  observe,  that  the  position  of  the  line  of 
coUimation  depends  upon  that  of  the  object-glass,  solely,  so 
that  the  eye-piece  may,  as  in  the  case  just  described,  be 
moved  in  any  direction,  or  even  entirely  removed  and  a  new- 
one  substituted,  without  at  all  deranging  the  adjustment  of 
the  wires. 

The  Standards. — In  order  that  the  wires  may  trace  a  ver- 
tical line  as  the  telescope  is  moved  up  or  down,  it  is  neces- 
sary that  both  the  standards  of  the  telescope  should  be  of 
precisely  the  same  height. 

To  ascertain  this  and  make  the  correction  if  needed,  pro- 
ceed as  follows: 

Having  the  line  of  collimation  previously  adjusted,  set  the 
instrument  in  a  position  where  points  of  observation,  such 
as  the  point  and  base  of  a  lofty  spire,  can  be  selected,  giving 
a  long  range  in  a  vertical  direction. 

Level  the  instrument,  fix  the  wires  on  the  top  of  the  object 
and  clamp  to  the  spindle;  then  bring  the  telescope  down, 
until  the  wires  bisect  some  good  point,  either  found  or 
marked  at  the  base;  turn  the  instrument  half  around,  fix  the 
wires  on  the  lower  point,  clamp  to  the  spindle,  and  raise  the 
telescope  to  the  highest  object. 

If  the  wires  bisect  it,  the  vertical  adjustment  is  effected; 
if  they  are  thrown  to  either  side  this  would  prove  that  the 
standard  opposite  that  side  was  the  highest,  the  apparent 
error  being  double  that  actually  due  to  this  cause. 

To  correct  it,  we  now  make  one  of  the  bearings  of  the  axis 
movable,  so  that  by  turning  a  screw  underneath  this  sliding 
piece,  as  well  as  the  screws  which  hold  on  the  cap  of  the 
standard,  the  adjustment  is  made  with  the  utmost  precision. 

This  arrangement,  which  is  common  to  all  our  telescope 
instruments,  is  very  substantial  and  easily  managed. 

The  Vertical  Circle. — When  this  attachment  requires  ad- 
justment, proceed  by  leveling  the  instrument  carefully,  and 


THE  VERNIER  TRANSIT. 


43 


having"  brought  into  line  the  zeros  of  the  wheel  and  vernier, 
find  or  place  some  well  defined  point  or  line  which  is  cut  by 
the  horizontal  wire. 

Turn  the  instrument  half  around,  revolve  the  telescope, 
and  fixing  the  wire  upon  the  same  point  as  before,  note  if 
the  zeros  are  again  in  line. 

If  not,  loosen  the  screws  and  move  the  zero  of  the  vernier 
over  half  the  error;  bring  the  zeros  again  into  coincidence, 
and  proceed  precisely  as  at  first  described  until  the  error  is 
entirely  corrected,  when  the  adjustment  will  be  completed- 

Should  it  be  desired,  at  any  time,  the  circle  can  be  removed 
by  the  surveyor  and  replaced  at  pleasure. 

The  Level  on  Telescope.— The  adjustment  of  this  will  be 
best  considered  when  we  come  to  speak  of  the  Surveyors' 
Transit. 

Adjustments  in  General. — We  ought  here  to  say  that  the 
above  adjustments,  as  well  as  all  the  others  which  we  have 
previously  explained  or  may  hereafter  describe,  are  always 
made  by  us  in  person,  but  are  given  in  this  work  in  order 
that  the  surveyor  and  engineer  may  fully  understand  theil 
instruments,  and  be  enabled  to  detect  and  remedy  errors  and 
accidents,  which  in  practice  will  often  occur. 

To  use  the  Vernier  Transit. 

This  instrument  is  used  on  the  ordinary  ball  and  spindle, 
placed  most  commonly  in  the  compass  tripod,  as  shown  ia 
the  engraving. 

Tripod  Head. — Sometimes  leveling  screws  with  the  parallui 
plates,  and  which  together  we  shall  designate  the  "  tripod 
head,''  with  a  clamp  and  tangent  movement,  are  used  with 
this  instrument  as  well  as  with  the  Surveyors'  Transit, 

This  tripod  head  can  be  unscrewed  from  the  legs,  and  is 
packed  in  the  instrument  box  ;  it  is  of  very  moderate  cost, 
and  in  almost  every  situation  is  infinitely  superior  to  a  ball 
and  socket  or  any  other  support. 


THE  VERNIER  TRANSIT. 

Compound  Ball. — We  also  manufacturG 
what  may  be  termed  a  compound  ball 
spindle/*  which  has  a  tangent  movement, 
and  gives  all  the  perfection  of  more  cost- 
ly arrangements,  with  a  very  moderate 
expense. 

As  represented  in  the  cut,  it  has  an  in- 
terior spindle,  around  which  an  outside 
hollow  cylinder  is  moved  by  turning  the 
double-headed  tangent  screw,  which  has 
in  the  middle  an  endless  screw,  working 
into  teeth  cut  spirally  around  in  a  groove 
of  the  cylinder.  The  compass,  or  other 
instrument,  revolves  on  the  outside  socket,  precisely  as  il 
placed  on  a  common  ball  spindle;  but  when  a  slower  move- 
ment is  required,  can  be  made  fast  by  the  clamp  screw,  and 
then  turned  gradually  around  the  interior  spindle  by  the  tan- 
gent screw,  until  the  slote  of  the  sight  or  the  intersection  of 
the  wires,  is  made  to  bisect  the  object  with  the  utmost  cer- 
tainty. 

The  compound  ball  may  be  placed  either  in  a  jacob-stafi 
socket  or  compass  tripod. 

Leveling  Socket. — A  convenient  arrangement  for  use, 
either  with  this  instrument  or  with  a  sight  compass,  is  shown 
'n  the  leveling  socket  described  in  our  account  of  the  solar 
compass  beyond. 

The  socket  may  be  used  either  with  the  ordinary  compass 
ball  or  the  compound  ball,  as  there  represented,  and  gives  a 
very  rapid  and  accurate  means  of  leveling  the  instrument. 

The  Spring  Catch,  described  in  our  account  of  the  Plain 
Compass,  is  always  attached  to  the  socket  of  this  instrument, 
whether  placed  upon  a  ball  or  tripod,  so  that  it  cannot  slip 
off  from  the  spindle  in  carrying. 

The  Clamp  Screw,  in  the  side  of  the  socket  of  this  instru- 


44 


[Fig.  9.] 


THE  VEBNIEK  TRANSIT. 


45 


ment,  is  shown  in  Fig  3,  and  by  pressing  a  brass  spring  in  the 
interior  against  the  spindle,  serves  to  fix  the  instrument  in  any 
position. 

The  Vernier  is  moved  by  the  pinion  head,  now  always 
placed  beneath  the  plate,  precisely  as  described  in  our  account 
of  the  Vernier  Compass,  and  is  read  to  minutes  in  the  same 
manner. 

There  is  also  a  clamp  nut  underneath  the  circle,  by  which  it 
is  securely  fixed  in  any  position,  which  must  be  loosened 
whenever  the  vernier  is  moved  by  the  pinion. 

The  Needle  Lifting  Screw  is  the  same  as  those  of  the 
compasses  previously  described. 

In  Surveying  with  this  instrument  the  operator  proceeds 
precisely  as  with  the  Vernier  Compass,  keeping  the  south 
end  towards  his  person,  reading  the  bearings  of  lines  from 
the  north  end  of  the  needle,  and  using  the  telescope  in  place 
of  sights,  revolving  it  as  objects  are  selected  in  opposite 
directions. 

Parallax. — Before  an  observation  is  made  with  the  tele- 
scope, the  eye-piece  should  be  moved  in  or  out  until  the  wires 
appear  distinct  to  the  eye  of  the  operator,  the  object-glass 
may  then  be  placed  in  position  by  turning  the  pinion  head 
on  the  top  of  the  telescope,  until  the  object  is  seen  clear  and 
well  defined,  and  the  wires  appear  as  if  fastened  to  its  sur- 
face. 

When,  on  the  contrary,  the  wires  are  not  perfectly  distinct, 
the  observer,  by  moving  his  eye  to  either  side  of  the  small 
aperture  of  the  eye  piece,  will  cause  the  wires  to  travel^' 
on  the  object,  and  thus  occasion  what  is  termed  the  *^  error 
of  parallax." 

The  intersection  of  the  wires  being  the  means  by  which 
the  optical  axis  of  the  telescope  is  defined,  should  be  brought 
precisely  upon  the  centre  of  the  object  to  which  the  instru- 
ment is  directed. 


46 


THE  VERNIER  TR.ANSIT. 


To  TAKE  Angles  of  Elevation". — Level  the  instrument  care- 
fully, fix  the  zeros  of  the  circle  and  vernier  in  line,  and  note 
the  height  cut  upon  the  staff  or  other  object,  by  the  horizon- 
tal wire;  then  carry  the  staff  up  the  elevation,  fix  the  v^ire 
again  upon  the  same  point,  and  the  angle  of  elevation  will 
be  read  off  by  the  vernier. 

By  careful  usage,  the  adjustments  of  the  Vernier  Transit 
will  remain  as  permanent  as  those  of  the  ordinary  compass, 
the  only  one  liable  to  derangement  being  that  of  the  line  of 
collimation. 

This  should  be  examined  occasionally,  and  corrected  in  the 
manner  previously  described. 

Bepairs  of  the  Vernier  Transit. 

These  being  in  great  part  already  spoken  of,  it  will  be 
necessary  to  consider  only  such  as  belong  to  the  telescope. 

To  Replace  the  Cross  Wires. — Take  out  the  eye-piece 
tube,  together  with  the  little  ring  by  which  it  is  centered, 
and  having  removed  two  opposite  cross-wire  screws,  with 
the  others  turn  the  ring  until  one  of  the  screw  holes  is 
brought  into  view  from  the  open  end  of  the  telescope  tube, 
in  this  thrust  a  stout  splinter  of  wood  or  a  small  wire  so  as 
to  hold  the  ring  when  the  remaining  screws  are  withdrawn  ; 
the  ring  is  then  taken  out  and  is  ready  for  the  wires. 

For  these  the  web  of  the  j^pider  is  to  be  preferred  above 
any  thing  else,  but  when  this  is  not  obtainable,  a  jSne  silk 
fibre  may  be  substituted. 

We  usually  procure  our  webs  from  the  living  manufacturer 
directly,  selecting  those  of  a  yellowish-brown  color,  as  fur- 
nishing the  most  perfect  product. 

The  spider  being  held  between  the  thumb  and  finger  of  an 
assistant,  in  such  position  as  to  suffer  no  serious  injury,  and 
at  the  same  time  be  unable  to  make  any  effectual  resistance 
with  his  extremities,  the  little  fibre  may  be  drawn  out  at 
pleasure,  and  being  placed  in  the  fine  lines  cut  on  the  surface 


THE  VERNIEE.  TRANSIT. 


47 


of  the  diaphragm,  is  then  firmly  cemented  to  its  place  by 
applying  softened  beeswax  with  the  point  of  a  knife  blade. 

In  case  the  spider  is  not  procurable,  a  fine  strand  of  a 
web  which  is  free  from  dust,  and  long  enough  to  serve  for 
both  wires,  may  be  selected. 

In  such  times  as  the  spiders  remain  in  their  winter  quar- 
ters, we  have  been  able  to  procure  very  good  fibres  from  a 
box  in  which  a  number  had  been  confined. 

When  the  wires  are  cemented,  the  ring  is  returned  to  its 
position  in  the  tube,  and  either  pair  of  screws  being  insert- 
ed, the  splinter  or  wire  is  removed,  and  the  ring  turned  until 
the  other  screws  can  be  replaced. 

Care  must  also  be  taken  that  the  same  side  of  the  ring  is 
turned  to  the  eye-piece  as  before  it  was  removed. 

When  this  has  been  done,  the  eye-tube  is  inserted,  and  its 
centering  ring  brought  into  such  a  position  that  the  screws 
in  it  can  be  replaced,  and  then  by  screwing  on  the  end  of  the 
telescope,  the  little  cover  into  which  the  eye-tube  is  fixed, 
the  operation  will  be  completed. 

To  Clean  the  Telescope. — The  only  glasses  that  will  ordi- 
narily require  cleaning,  are  the  object-glass  on  its  outside 
surface,  and  the  little  eye-lens^  which  is  exposed  when  the 
cap  of  the  eye-tube  is  removed. 

To  remove  the  dust  from  these  use  a  very  soft  and  clean 
silk  or  cotton  cloth,  and  be  careful  not  to  rub  the  same  part 
of  the  cloth  a  second  time  on  the  surface  of  the  glass. 

No  one  should  ever  be  allowed  to  touch  the  glasses  with 
the  fingers  or  with  a  dusty  cloth. 

Excellencies  of  the  Vernier  Transit, 
These  are  due  chiefly  to  the  telescope  and  its  attachments, 
and  from  what  has  already  been  said,  it  will  appear  are  such 
as  to  render  this  instrument  greatly  superior  to  one  provided 
with  the  ordinary  sights. 

I.  The  magnifying  power  of  the  telescope  enables  the  sur- 


48 


THE  VERNIER  TRANSIT. 


veyor  to  take  accurate  observations  at  distances  entirely 
beyond  the  reach  of  the  naked  eye. 

2.  The  fine  intersection  of  the  cross-wires  can  be  set  pre- 
cisely upon  the  centre  of  the  object. 

3.  The  revolving  property  of  the  telescope  gives  the  meang 
of  running  lang  lines  up  or  down  steep  ascents  or  descents 
with  perfect  ease,  where,  with  the  short  sights  of  the  ordi- 
nary compass,  two  or  three  observations  would  have  to  be 
taken. 

4.  The  u&e  of  a  telescope  entirely  avoids  the  incessant  trying 
of  the  eyes,  experienced  in  surveys  with  the  ordinary  sights. 

5.  With  the  telescope,  lines  can  be  run  through  the  forest 
or  brush v/ood,  and  the  flagstaff  distinguished  with  much 
greater  certainty  than  through  the  sights  of  a  compass. 

This  statement  may  appear  very  unreasonable  to  those  not 
familiar  with  the  instrument,  and  these,  in  fact,  raise  the 
greatest  objection  to  a  telescope,  from  its  supposed  unfitness 
for  surveys  in  such  locations. 

They  have  only  to  use  it  a  few  times  in  this  kind  of  work, 
in  connection  with  a  flagstaff,  painted  white  or  covered  with 
paper,  to  distinguish  it  from  the  surrounding  objects,  to  be 
convinced  of  its  great  superiority. 

In  the  Vernier  Transit,  as  furnished  by  us,  is  supplied,  as 
we  believe,  to  the  surveyor  the  most  perfect  of  all  needle 
instruments,  and  this  at  a  cost  but  little  above  that  charged 
by  other  makers  for  a  sight  compass. 

The  advantages  of  the  telescope  and  its  attachments  are 
so  great  that  a  surveyor,  accustomed  to  them,  would  find  it 
difficult  to  content  himself  with  the  ordinary  compass,  and 
such  in  fact  is  the  universal  testimony  of  those  familial  with 
the  Vernier  Transit. 

Weight  of  the  Vernier  Transit. 

The  weight  of  this  instrument,  exclusive  of  the  tripod  legs, 
and  with  a  plain  telescope,  is  about  ten  pounds. 


THE  VERNIER  TRANSIT. 


49 


Sizes  of  the  Vernier  Transit, 

We  make  three  sizes,  having  respectively  needles  of  four, 
five  and  six  inches  long. 

The  telescopes  of  our  five  and  six  inch  transits,  are  both 
eleven  inches  long,  and  reverse  at  either  end  ;  the  telescope  of 
the  four  inch  size  is  about  seven  inches,  and  the  whole  instru- 
ment very  light  and  portable. 

Weights  of  the  Vernier  Transits. 
The  average  weights  of  the  difi*erent  sizes,  not  including  the 
tripods  are,  for  the  four  inch  instrument,  five  pounds  ;  the  five 
inch,  eight,  and  the  six  inch,  ten  pounds. 


ft 


50 


NEEDLE  INSTRUMEN.TS, 


ISTeedle  InstrTaments. 


We  have  now  described  the  instruments  included  under 
the  division  termed  Needle  Instruments,  in  the  beginning  of 
this  work. 

As  there  stated,  the  Plain  and  Vernier  Compasses  and  the 
Vernier  Transit  depend  for  their  accuracy  and  value,  mainly 
upon  the  perfection  of  movement  of  the  magnetic  needle. 

With  such  instruments,  the  greater  part  of  the  surveying 
in  our  country  has  been,  and  will  for  a  long  time  in  the  future, 
continue  to  be  done. 

And  though  with  the  improvements  made  in  these  instru- 
ments, a  good  surveyor  may,  with  great  care  and  skill,  do 
work  with  a  surprising  degree  of  accuracy  and  perfection, 
yet  all  needles  are  liable  to  many  irregularities. 

Imperfections  of  the  Needle, 

These  may  arise  either  from  the  loss  of  magnetic  virtue  in 
the  poles,  the  blunting  of  the  centre-pin,  or  the  attraction 
exerted  upon  it  by  bodies  of  iron,  whose  presence  may  be 
entirely  unsuspected. 

The  two  first  of  these  errors  may  be  easily  remedied  in  the 
manner  we  have  described. 

Local  Attraction. — The  third  and  most  frequent  source  of 
inaccuracy,  may  be  detected  by  taking  back  sights,  as  well 
as  fore  sights,  upon  every  line  run  with  the  needle,  and  by 
the  agreement  of  the  bearings,  determining  the  true  direc- 
tion of  the  line. 

Sometimes  a  compass  may  have  little  panicles  of  iron  con- 
cealed within  the  surface  of  the  metal  circ^J  or  plates. 


NEEDLE  INSTRUMENTS. 


51 


It  is  the  business  of  the  maker  to  examine  every  instru- 
ment, in  search  of  this  defect,  by  trying  the  reversion  of  the 
needle  upon  all  points  of  the  divided  circle. 

If  the  needle  should  fail  to  reverse,  when  the  compass  is 
turned  half  around,  and  the  sights  directed  a  second  time 
upon  any  object,  the  instrument  should  be  thrown  aside  and 
never  sold. 

Besides  the  dificulties  caused  by  the  above  imperfections, 
the  variation  of  the  needle  is  a  frequent  source  of  annoyance. 

What  is  termed  the  secular  variation,  we  have  already 
mentioned  in  our  acccount  of  the  Vernier  Compass,  we  will 
now  speak  of  the 

Diurnal  Variation. — This  is  owing  to  the  influence  of  the 
sun,  which,  in  summer,  will  cause  the  needle  to  vary  from 
ten  to  fifteen  minutes  in  a  few  hours,  when  .exposed  to  its 
fullest  influence. 

To  guard  against  these  causes  of  inaccuracy  in  the  use  of 
needle  instruments,  the  surveyor  will  need  the  greatest  care 
and  attention  ;  and  yet,  with  all  the  precautions  than  can  be 
suggested,  the  difiiculty  of  measuring  horizontal  angles  with 
certainty,  and  to  a  sufficient  degree  of  minuteness  by  the 
needle  alone,  has  caused  a  demand  to  be  felt  more  and  more 
sensibly  in  all  parts  of  the  country  for  instruments,  in  the 
use  of  which  the  surveyor  may  proceed  with  assured  accu- 
racy and  precision. 

Indeed,  in  Canada,  so  great  is  the  distrust  of  needle  in- 
struments, that  the  Provincial  Land  Surveyors  are  forbidden 
to  use  an  instrument  in  their  land  surveys,  unless  it  is  capable 
of  taking  angles  independently  of  the  needle. 

To  supply  the  demand  thus  created  for  increased  perfection 
in  the  implements  of  the  surveyor,  we  manufacture  a  variety 
'^f  instruments  ;  three  of  which  we  shall  now  describe  under 
the  names  of  The  Railroad  Compass,  The  Surveyor's  Transit^ 
and  the  Solar  Compass. 


52 


THE  RAILROAD  COMPASS. 


BTarveying  Instrninents. 


THE  KAILROA^  COMPASS. 

Fig.  10. 


As  shown  in  Fig.  10,  this  instrument  has  the  main  plate, 
levels,  sights,  and  needle  of  the  ordinary  instrument,  and 
has  also  underneath  the  main  plate  a  divided  circle  or  limb 
by  which  horizontal  angles  to  single  minutes  can  be  taken 
independently  of  the  needle. 

The  verniers  are  attached  to  the  under  surface  of  the  main 
plate  the  openings  through  which  they  are  seen  being  covered 
with  slips  of  glass  to  protect  the  divisions  from  dust  and 
moisture;  only  one  of  the  verniers  is  shown  in  the  cut. 

The  connection  between  the  two  plates  is  made  by  a  clamp 
and  tangent  movement  shown  at  e,  by  which  they  can  be  fas- 


THE  RAILROAD  COMPASS. 


53 


tened  together  or  released  at  will,  or  moved  slowly  around 
each  other  as  may  be  desired  in  the  use  of  the  compass. 

The  needle  lifting  screw  is  shown  near  the  clamp  screw, 
on  the  same  end  of  the  plate. 

On  the  opposite  side  of  the  compass  circle  is  seen  the  head  a 
of  a  pinion  working  into  a  circular  rack  fixed  to  the  edge  of 
the  compass  circle,  and  thus  enabling  the  surveyor  to  move  the 
compass  circle  about  its  centre  in  setting  off  the  variation  of 
the  needle,  precisely  as  in  the  case  of  the  vernier  compass. 

The  variation  is  read  to  single  minutes  by  a  vernier  and 
divided  arc,  partially  shown  near  the  letter  S  in  the  cut. 

Near  the  pinion  head  is  also  shown  a  clamp  screw,  by  which 
the  circle  is  securely  fixed  when  moved  to  the  proper  position. 

The  sockets  upon  which  the  plates  of  this  instrument  turn 
are  long  and  well  fitted,  and  the  movement  of  the  vernier 
plate  around  the  limb  is  almost  perfectly  free  from  friction. 

The  graduated  circle  or  limb  is  divided  to  half  degrees, 
and  figured  in  two  rows,  viz  :  from  0^  to  90^,  and  from  0^  to 
860^;  sometimes  but  a  single  series  is  used,  and  then  the 
figures  run  from  0°  to  360^,  or  from  0^  to  180^  on  each  side. 

The  figuring,  which  is  the  same  upon  this  as  in  the  other 
angular  instruments  we  shall  hereafter  describe,  is  varied 
when  desired  by  the  surveyor.  The  first  method  is  our 
usual  practice. 

The  Verniers  are  double,  having  on  each  side  of  the  zero 
mark  thirty  equal  divisions  corresponding  precisely  with 
twenty-nine  half  degrees  of  the  limb;  they  thus  read  to 
single  minutes,  and  the  number  passed  over  is  counted  in 
the  same  direction  in  which  the  vernier  is  moved. 

The  use  of  two  opposite  verniers  in  this  and  other  instru- 
ments gives  the  means  of  cross  questioning^'  the  gradua- 
tions, the  perfection  with  which  they  are  centered  and  the 
dependence  which  can  be  placed  upon  the  accuracy  of  the 
angles  indicated. 


54 


THE  RAILROAD  COMPASS. 


The  Needle  of  this  instrument  is  about  five  and  a  half  iiichea 
long,  and  made  precisely  like  those  previously  described. 

The  Adjustments  of  this  instrument,  with  which  the  sur- 
veyor will  have  to  do,  have  been  already  described. 

To  use  the  Railroad  Compass. 

It  can  be  set  upon  the  common  compass  ball,  or  still  better, 
the  tangent  ball  already  described,  placed  either  in  a  jacob- 
staff  socket,  a  compass  tripod,  or  the  leveling  socket  and 
tripod  as  shown  with  the  solar  compass. 

We  have  also  adapted  to  many  of  these  instruments,  the 
leveling  tripod  head,  with  clamp  and  tangent  movement,  and 
this  is  preferable  to  any  other  support. 

To  TAKE  Horizontal  Angles. — First  level  the  plate  and 
set  the  limb  at  zero,  fix  the  sights  upon  one  of  the  objects 
selected,  and  clamping  the  whole  instrument  firmly  to  the 
spindle,  unclamp  the  vernier  plate  and  turn  it  with  the  hand, 
until  the  sights  are  brought  nearly  upon  the  second  object ; 
then  clamp  to  the  limb,  and  with  the  tangent  screw  fix  them 
precisely  upon  it. 

The  number  of  degrees  and  minutes  read  off  by  the  vernier, 
tvill  give  the  angle  between  the  two  objects,  taken  from  the 
centre  of  the  instrument. 

It  will  be  understood  that  the  horizontal  angles  can  be 
taken  in  any  position  of  the  verniers,  with  reference  to  the 
zero  point  of  the  limb  ;  we  have  given  that  above  as  being 
the  usual  method  and  liable  to  the  fewest  errors. 

It  is  advisable  where  great  accuracy  is  required,  in  this 
and  other  instruments  furnished  with  two  verniers,  to  obtain 
the  readings  of  the  limb  from  both,  add  the  two  together  and 
halve  their  sum  ;  the  result  will  be  the  mean  of  the  two 
readings,  and  the  true  angle  between  the  points  observed. 

Such  a  course  is  especially  necessary  when  the  readings 
of  the  verniers  essentially  disagree,  as  may  sometimes  hap- 
pen when  the  instrument  has  been  injured  by  an  accident. 


THE  RAILROAD  COMPASS. 


55 


Use  of  the  Needle. — In  taking  horizontal  angles  as  just 
described,  the  magnetic  bearings  of  the  two  objects  are 
often  noted,  and  thus  two  separate  readings  of  the  same 
angle,  one  by  the  limb,  the  other  by  the  needle,  are  obtained, 
to  be  used  as  checks  upon  each  other  to  prevent  mistakes. 

To  Turn  off  the  Variation  of  the  Needle. — Having  leveled 
the  instrument,  set  the  limb  at  zero,  and  place  the  sights 
upon  the  old  line,  note  the  reading  of  the  needle,  and  make 
it  agree  with  that  given  in  the  field  notes  of  the  former 
survey,  by  turning  the  compass  circle  about  its  centre  by 
the  pinion  a. 

Now,  clamp  the  compass  circle  firmly  by  the  clamp  screw, 
and  the  number  of  degrees  or  minutes  passed  over  by  the 
vernier  of  the  compass  circle  will  be  the  change  of  variation 
in  the  interval  between  the  two  surveys. 

To  Survey  with  this  instrument,  the  operator  should  turn 
the  south  side  of  the  compass  face  towards  his  person,  and 
having  brought  the  zeros  of  the  limb  and  vernier  plate  in 
contact,  clamp  them,  and  proceed  as  directed  in  our  account 
of  the  Plain  Compass. 

Of  course  it  will  be  understood  that  lines  can  be  run  and 
angles  measured  by  the  divided  limb  and  verniers,  entirely 
independent  of  the  needle,  which,  in  localities  where  local 
attraction  is  manifested,  is  very  serviceable. 

The  accuracy  and  minuteness  of  horizontal  angles  indi- 
cated by  this  instrument,  together  with  its  perfect  adapta- 
tion to  all  the  purposes  to  which  the  Vernier  Compass  can 
be  applied,  have  brought  it  into  use  in  many  localities, 
where  the  land  is  so  valuable  as  to  require  more  careful  sur- 
veys than  are  practicable  with  a  needle  instrument. 

Weight  of  the  Railroad  Compass. 
The  average  weight  of  this  instrument,  including  the  brass 
head  of  the  jacob  staff,  is  about  11^  lbs. 


5(5 


THE  RAILKOAD  COMPASS. 


Single  Vernier  Railroad  Compass. 

We  Lave  just  introduced  a  new  style  of  this  instrument, 
essentially  alike  that  already  described,  but  of  somewhat 
simpler  construction  in  its  sockets,  and  having  but  a  single 
vernier  to  the  limb. 

This  new  instrument,  though  afforded  at  a  price  materially 
lower  than  the  other,  is  still  in  every  way  accurate  and  reliable. 

Sizes  and  Weights  of  the  Railroad  Compass, 

We  make  two  sizes  of  this  instrument,  viz. :  five,  and  five 
and  a  half  inch  needle ;  the  largest  size,  including  the  brass 
head  of  the  Jacob  staff,  weighing  ten,  and  the  five  inch,  nine 
pounds. 

The  Double  Vernier  Compass  has  a  five  and  a  half  inch 
needle,  and  weighs,  with  ball  and  socket,  about  eleven  pounds. 

We  invite  especial  attention  to  the  different  styles  of  our 
Railroad  compasses,  believing  that  in  many  respects  they  are 
very  much  superior  to  any  other  compass  made,  having  a  hori- 
zontal limb,  and  an  arrangement  by  which  the  variation  of  the 
needle  can  be  so  readily  set  off  and  ascertained. 


Made  l)y 


BE'NJ  D.  BENSON.  ITX  " 


THE  surveyor's  TRANSIT. 


57 


THE  SURVEYOR'S  TRANSIT. 
This  instrument  shown  in  the  engraving*  on  the  opposite 
page,  is  in  principle  very  similar  to  the  instrument  just  de- 
scribed, diiTering  from  it  mainly  in  the  substitution  of  the 
telescope  with  its  appendages,  for  the  ordinary  compass 
Bights. 

The  Telescope  is  of  somewhat  finer  quality  than  that  used 
with  the  Vernier  Transit;  as  here  shown,  it  is  furnished  with 
a  small  level,  having  a  ground  bubble  tube  and  a  scale;  and 
also  a  vertical  circle  connected  v/ith  its  axis. 

The  Standards  are  made  precisely  like  those  of  the  Vernier 
Transit,  the  bearings  of  the  axis  of  the  telescope  being  con- 
ical, and  fitted  with  the  utmost  nicety;  there  is  also  in  one 
of  them  the  moveable  piece  for  the  adjustment  of  the  wires 
to  the  tracing  of  a  vertical  line. 

The  Spirit  Levels  are  placed  upon  the  upper  surface  of  the 
vernier  plate,  one  being  fixed  on  the  standard  so  as  not  to 
obstruct  the  light  which  falls  on  the  vernier  opening  beneath. 

Both  levels  are  adjustable  with  the  ordinary  steel  pin. 

The  Needle  is  like  that  of  the  previous  instrument,  but  is 
only  five  inches  long. 

The  Vernier  Plate,  which  carries  the  verniers  and  tele- 
scopes, is  made  to  move  with  perfect  ease  and  stability, 
around  the  graduated  circle  or  limb,  and  horizontal  angles 
are  taken  to  single  minutes;  the  variation  of  the  needle  is 
also  set  off  by  the  pinion  and  clamp  screw,  as  described  in 
the  account  of  the  previous  instrument. 

The  Verniers,  as  in  all  our  angular  instruments,  are  double, 
reading  either  way  from  the  centre  mark,  and  to  single 
minutes  of  a  degree. 

There  are  two  verniers,  placed  on  opposite  sides  of  the 
instrument  at  right  angles  to  the  telescope;  only  one  of 
these  is  shown  in  the  cut. 


58 


THE  surveyor's  TRANSIT. 


The  Divided  Circle,  or  limb,  is  graduated  to  half  degrees, 
reads  to  minutes  by  the  verniers,  and  is  figured  as  described 
before. 

The  Clamp  and  Tangent  movement  of  the  vernier  plate  is 
the  same  as  that  of  the  Railroad  Compass;  it  is  well 
shown  in  the  figure. 

The  Tripod  Head. — This  instrument,  as  shown  in  the 
engraving,  is  generally  used  on  a  leveling  tripod. 

The  Light  Leveling  Tripod,  used  with  the  Surveyor's  Tran- 
sit, is  well  shown  in  the  engraving.  As  there  seen,  there  are 
nuts  screwed  in  to  the  upper  parallel  plate,  so  as  to  give  a 
long  bearing  for  the  four  leveling  screws. 

The  under  plate  supports  the  feet  of  the  screws,  and  has 
beneath  a  cavity  or  bowl,  in  which  moves  a  hemispherical 
nut  screwed  to  the  spindle  of  the  tripod. 

This  nut  serves  both  to  connect  the  plates  together,  and 
as  a  pivot  on  which  the  upper  plate  is  turned  by  the  leveling 
screws. 

The  under  parallel  plate  has  also  a  screw  on  the  under  side, 
by  which  the  tripod  head  maybe  disconnected  from  the  legs, 
and  packed  in  the  box  with  the  instrument. 

The  leveling  screws  are  made  of  bell  metal,  have  a  large 
iouble  milled  head,  and  a  deep  screw  of  about  forty  threads 
lo  the  inch;  their  ends  set  into  little  brass  cups,  so  that  the 
screws  are  worked  without  indenting  the  under  plate. 
Sometimes  a  piece  of  leather  is  put  in  place  of  the  cups. 

The  leveling  screws  are  entirely  covered  above  by  little 
caps  which  screw  over  the  upper  side  of  the  nut. 

When  the  screws  are  loosened,  the  upper  plate  can  be 
shifted  around,  so  as  to  bring  the  leveling  screws  in  any  po- 
sition, with  reference  to  the  plates  and  telescope  of  the  in- 
strument. 

The  clamp  and  tangent  screws  are  seen  on  the  upper  plate 
of  the  tripod.    In  place  of  the  single  tangent  screw,  we  have, 


THE  surveyor's  TRANSIT. 


59 


in  all  our  instruments,  substituted  the  double  tangent  move- 
ment, as  shown  in  the  engraving*. 

The  spindle  of  the  tripod  head  rises  above  the  upper  plate, 
and  the  instrument  can  be  removed  from  it,  by  pulling  out 
a  little  pin  made  to  spring  into  a  groove,  and  thus  keep  the 
instrument  from  falling,  when  the  tripod  is  carried  upon  the 
shoulder. 

In  th«  lower  end  of  the  spindle  and  underneath  the  plates, 
is  screwed  the  loop  for  attaching  the  string  of  the  plumb-bob. 

To  Level  the  Tripod,  the  engineer  takes  hold  of  the  oppo- 
site screw  heads  with  the -thumb  and  fore  finger  of  each  hand, 
and  turning  both  thumbs  in  or  out,  as  may  be  necessary, 
raises  one  side  of  the  upper  parallel  plate  and  depresses  the 
other,  until  the  desired  correction  is  made. 

Shifting  the  Tripod  Head. — A  simple  arrangement  by 
which  an  instrument  can  be  easily  set  over  a  given  point,  is 
made  by  extending  the  stem  of  the  tripod  head  below, 
through  a  large  circular  aperture  in  the  centre  of  the  plate 
to  which  the  legs  are  attached,  so  as  to  connect  by  the 
hemispherical  nut  or  pivot,  with  a  little  moveable  piece 
bearing  on  the  under  surface  of  the  plate.  The  leveling 
screws  of  course,  rest  directly  on  the  upper  surface  of  this 
plate,  and  when  loosened,  can  be  shifted  nearly  an  inch  from 
side  to  side  in  any  direction  ;  thus  allowing  the  point  of  the 
plumb-bob,  to  be  set  directly  over  a  given  point  on  the 
ground. 

This  modification  requires  a  larger  tripod,  and  gives  the 
surveyor  a  little  more  trouble  when  the  tripod  head  is  de- 
tached from  the  legs. 

It  is  not  so  easily  adapted  to  the  Engineer's  Transit,  as  to 
our  other  instruments,  nor  can  so  much  movement  be  secured, 
but  is  made  by  us  for  any  instrument  whenever  desired  and 
without  additional  charge. 

Adjusting  Socket,  a  beautiful  arrangement  for  occasional 


60 


THE  surveyor's  TRANSIT. 


use  in  place  of  the  leveling  tripod,  in  cases  where  greater 
lightness  and  rapidity  of  adjustment  are  desired,  is  shown  in 
the  adjusting  socket,  described  in  the  account  of  the  Solar 
Compass. 

To  adjust  the  Surveyor's  Transit. 

The  Levels  are  adjusted  with  a  steel  pin  as  those  of  the  • 
Vernier  Transit,  and  it  need  only  be  added  here,  that  in  this, 
as  well  as  other  instruments  having  two  plates,  moving  upon 
sockets  independent  of  each  other,  the  levels,  when  adjusted 
on  one  plate,  should  still  keep  their  position  when  both  are 
clamped  together  and  turned  upon  a  common  socket. 

Otherwise,  however  accurately  the  telescope  might  trace 
a  vertical  line,  when  revolved  upon  the  socket  of  one  plate, 
it  would  give  a  very  different  result  as  soon  as  the  position 
of  the  other  plate  was  changed. 

The  Needle  and  telescope  with  its  other  attachments  being 
adjusted,  as  described  in  our  account  of  the  Vernier  Transit, 
we  shall  here  consider  only  that  of  the 

Level  on  Telescope. — For  the  adjustment  of  this  attach- 
ment we  shall  give  two  methods,  the  first  being  that  usually 
practiced  by  us. 

1.  First  level  the  instrument  carefully,  and  with  the  clamp 
and  tangent  movement  to  the  axis,  make  the  telescope  hori- 
zontal as  near  as  may  be  with  the  eye,  then  having  the  line 
of  collimation  previously  adjusted,  drive  a  stake  at  a  con- 
venient distance,  say  from  one  to  three  hundred  feet,  and 
note  the  height  cut  by  the  horizontal  wire,  upon  a  staff  set 
on  the  top  of  the  stake. 

Fix  another  stake  in  the  opposite  direction,  and  at  the 
same  distance  from  the  instrument,  and  without  disturbing 
the  telescope,  turn  the  instrument  upon  its  spindle,  "set  the 
staff  upon  the  stake,  and  drive  in  the  ground,  until  the  same 
height  is  indicated  as  in  the  first  observation. 

The  top  of  the  two  stakes  will  then  be  in  the  same  hcri- 


THE  surveyor's  TRANSIT. 


61 


zontal  line,  however  much  the  telescope  may  be  out  of 
level. 

Now  remove  the  instrument  from  fifty  to  one  hundred  feet 
to  one  side  of  either  of  the  stakes,  and  in  line  with  both  ; 
again  level  the  instrument,  clamp  the  telescope  as  nearly 
horizontal  as  may  be,  and  note  the  heights  indicated,  upon 
the  staff  placed  first  upon  the  nearest,  and  then  upon  the 
most  distant  stake. 

If  both  agree,  the  telescope  is  level ;  if  not,  with  the 
tangent  screw  move  the  wire  over  nearly  the  whole  error,  as 
shown  at  the  distant  stake,  and  repeat  the  observation  as 
just  described.  Proceed  thus  until  the  horizontal  wire  will 
indicate  the  same  height  at  both  stakes,  when  the  telescope 
will  be  truly  horizontal. 

Taking  care  not  to  disturb  its  position,  bring  the  bubble 
into  the  centre  by  the  little  leveling  nuts  .at  the  end  of  the 
tube,  when  the  adjustment  will  be  completed. 

2.  Choose  a  piece  of  ground  nearly  level,  and  having  set 
the  instrument  firmly,  level  the  plates  carefully,  and  bring 
the  bubble  of  the  telescope  into  the  centre  with  the  tangent 
screw.  Measiu'e  in  any  direction  from  the  instrument,  from 
one  to  three  hundred  feet,  and  drive  a  stake,  and  on  the  stake 
set  a  staff  and  note  the  height  cut  by  the  horizontal  wire, 
then  take  the  same  distance  from  the  instrument  in  an  oppo 
site  direction,  and  drive  another  stake. 

On  that  stake  set  the  staff  and  note  the  height  cut  by  the 
wire  when  the  telescope  is  turned  in  that  direction. 

The  difference  of  the  two  observations  is  evidently  the 
difference  of  level  of  the  two  stakes. 

Set  the  instrument  over  the  lowest  stake,  or  that  upon 
which  the  greatest  height  was  indicated,  and  bring  the 
levels  on  the  plates  and  telescope  into  adjustment  as  at  first. 

Then  with  the  staff,  measure  the  perpendicular  distance 
from  the  top  of  the  stake  to  the  centre  cf  one  of  the  horizontal 


62 


THE  surveyor's  TRANSIT. 


co-OSS  wire  screw  heads ;  from  that  distance  subtract  the  dif- 
ference of  level  between  the  two  stakes  and  mark  the  point 
on  the  staff  thus  found ;  place  the  staff  on  the  other  stake, 
and  with  the  tangent  screw  bring  the  horizontal  wire  to  the 
mark  just  found,  and  the  line  will  be  level. 

The  telescope  now  being  level,  bring  the  bubble  of  the 
level  into  the  centre,  by  turning  the  little  nuts  at  the  end  of 
the  tube,  and  noting  again  if  the  wires  cut  the  point  on  the 
staff;  screw  up  the  nuts  firmly  and  the  adjustment  will  be 
completed. 

With  such  a  level  carefully  adjusted,  the  engineer,  by  tak- 
ing equal  fore  and  back  sights,  can  run  horizontal  lines  with 
great  rapidity,  and  a  good  degree  of  accuracy.  ' 

To  use  the  Surveyor's  Transit. 

In  surv^eying  with  this  instrument,  the  plates  must  be  set  so 
that  the  zeros  of  the  circle  and  the  verniers  correspond,  and 
firmly  clamped  together,  the  eye  end  of  the  telescope  being 
placed  over  the  south  side  of  the  compass  circle,  in  the  posi 
tion  shown  in  the  engraving. 

The  surveyor  may  then  proceed  precisely  as  with  the  plain 
compass. 

To  TURN  OFF  Angles. — When  angles  are  to  be  measured 
independently  of  the  needle,  proceed  precisely  as  directed  in 
the  description  of  the  Railroad  Compass. 

The  Variation  of  the  Needle  is  also  set  off  as  men- 
tioned in  our  account  of  that  instrument. 

Sizes  of  the  Surveyor's  Transit. 
We  make  three  sizes  of  this  instrument,  the  weights  and 
dimensions  of  limb  of  each  being  as  follows: 

4  inch  needle,  horizontal  limb,  6  in.  diameter,  weight  12  lbs. 

5  6J  13  ' 


Si  ii'pjic  Vcrii  icr 


Made  by 

W.&jLJE.GlLIKlLlEY, 

EENJ  D.  BENSON  K  T. 


THE  surveyor's  TRANSIT. 


63 


Single  Vernier  Surveyor"*  s  Tiamit 

We  have  just  introduced  a  modification  of  this  favorite 
instrument,  by  which,  with  a  lighter  socket  and  one  double 
vernier  to  the  limb,  we  furnish  all  the  capabilities  of  the  more 
costly  instrument,  at  a  material  reduction  in  price. 

We  make  three  sizes  of  this  transit,  of  the  same  dimensions 
as  those  having  two  verniers  to  the  limb ;  the  engraving 
opposite  represents  the  one  with  five  inch  needle,  having  also 
a  level  attached  to  telescope,  with  clamp  and  tangent  to  axis. 

This  instrument  may  be  used  on  the  hall  spindle  and  com- 
pass tripod,  like  the  Vernier  Transit,  but  like  other  transits 
should  also  be  furnished  with  the  usual  leveling  tripod. 

The  Single  Vernier  Surveyor's  Transit,  from  its  lightness, 
excellence  and  cheapness,  will  supply  as  we  trust,  a  need  long 
felt  by  engineers  and  surveyors,  in  furnishing  an  instrument 
suitable  for  accurate  work  at  a  very  reasonable  cost. 

Merits  of  the  Surveyor^  s  Transit, 
In  this  instrument,  as  just  described,  the  surveyor  will 
recognize  advantages  not  possessed  by  any  other  instrument 
with  which  we  are  acquainted. 

Combining  the  capabilities  of  a  needle  instrument,  with  a 
fine  telescope,  and  the  accuracy  of  a  divided  limb  and  verniers, 
and  having  also  the  means  for  turning  off  the  variation  of  the 
needle;  it  is  for  a  mixed  practice  of  accurate  surveying  and 
engineering,  such  indeed  as  is  required  by  most  city  engineers, 
the  best  instrument  ever  constructed. 

The  peculiar  construction  of  the  sockets  and  plates  of  this 
instrument  is  entirely  our  own  invention,  and  we  feel  the 
utmost  confidence  in  recommending  it  to  all  whose  practice  ia 
such  as  to  require  the  use  of  the  needle  combined  with  that  of 
the  divided  circle  and  verniers. 


64 


THE  SOLAR  COMPASS. 


THE  SOLAR  COMPASS. 

This  instrument,  so  ingeniously  contrived  for  readily  deter 
mining  a  true  meridian  or  north  and  south  line,  was  invented 
by  William  A.  Burt,  of  Michigan,  and  patented  by  him  in  1836. 

It  has  since  come  into  general  use  in  the  surveys  of  U.  S. 
public  lands,  the  principal  lines  of  which  are  required  to  be 
run  with  reference  to  the  true  meridian. 

The  invention  having  long  since  become  the  property  of 
the  public,  we  have  given  our  attention  to  the  manufacture 
of  these  instruments,  and  are  now  prepared  to  furnish  them, 
with  important  improvements  of  our  own  devising,  at  greatly 
reduced  prices. 

Our  improved  Solar  Compass,  one  form  of  which  is  shown  in 
the  engraving,  has  nearly  the  same  arrangement  of  plates,  with 
divided  circles,  verniers,  and  sockets,  as  the  Railroad  Compass. 

The  Solar  Apparatus, 

The  Solar  Apparatus  is  seen  in  the  place  of  the  needle, 
and  in  fact  operates  as  its  substitute  in  the  field. 

It  consists  mainly  of  three  arcs  of  circles,  by  which  can 
be  set  off  the  latitude  of  a  place,  the  declination  of  the  sun, 
and  the  hour  of  the  day. 

These  arcs,  designated  in  the  cut  by  the  letters  a,  6,  and 
c,  are  therefore  termed  the  latitude,  the  declination,  and  the 
hour  arcs  respectively. 

The  Latitude  Arc,  a,  has  its  centre  of  motion  in  two  pivots 
one  of  which  is  seen  at  J,  the  other  is  concealed  in  the  cut. 

It  is  moved  either  up  or  down  within  a  hollow  arc,  seen 
in  the  cut,  by  a  tangent  screw  at  /,  and  is  securely  fastened 
in  any  position  by  a  clamp  screw. 

The  Latitude  arc  is  graduated  to  quarter  degrees,  and 
reads  by  its  vernier,  e,  to  single  minutes  ;  it  has  a  range  of 
about  thirty-five  degrees,  so  as  to  be  adjustable  to  the  lati- 
tude of  any  place  in  the  United  States. 


THE  SOLAR  COMPASS. 


65 


The  Declination  Arc,  6,  is  also  graduated  to  quarter 
degrees,  and  has  a  range  of  about  twenty-four  degrees. 

Its  vernier,  v,  reading  to  single  minutes,  is  fixed  to  a 
movable  arm,  /i,  having  its  centre  of  motion  in  the  centre 
of  the  declination  arc  at  g  ;  the  arm  is  moved  over  the  sur- 
face of  the  declination  arc,  and  its  vernier  set  to  any  reading 
by  turning  the  head  of  the  tangent  screw,  k.  It  is  also  securely 
clamped  in  any  position  by  a  screw,  concealed  in  the  engraving. 

Solar  Lenses  and  Lines.— At  each  end  of  the  arm,  h,  is  a 
rectangular  block  of  brass,  in  which  is  set  a  small  convex 
lens,  having  its  focus  on  the  surface  of  a  little  silver  plate, 
fastened  by  screws  to  the  inside  of  the  opposite  block. 

The  silver  plate,  with  its  peculiar  lines,  will  be  referred  to 
more  particularly  hereafter. 

Equatorial  Sights.— On  the  top  of  each  of  the  rectangular 
blocks  is  seen  a  little  sighting  piece,  termed  the  equatorial 
Bight  fastened  to  the  block  by  a  small  milled  head  screw,  so 
as  to  be  detached  at  pleasure. 

They  are  used,  as  will  be  explained  hereafter,  in  adjusting 
the  different  parts  of  the  solar  apparatus. 

The  Hour  Arc,  c,  is  supported  by  the  two  pivots  of  the 
latitude  arc,  already  spoken  of,  and  is  also  connected  with 
that  arc  by  a  curved  arm,  as  shown  in  the  figure. 

The  hour  arc  has  a  range  of  about  120^,  is  divided  to  half 
degrees,  and  figured  in  two  series  ;  designating  both  the 
hours  and  the  degrees,  the  middle  division  being  marked  12 
and  90  on  either  side  of  the  graduated  lines. 

The  Polar  Axis. — Through  the  centre  of  the  hour  arc 
passes  a  hollow  socket,  p,  containing  the  spindle  of  the 
declination  arc,  by  means  of  which  this  arc  can  be  moved 
from  side  to  side  over  the  surface  of  the  hour  arc,  or  turned 
completely  round  as  may  be  required. 

The  hour  arc  is  read  by  the  lower  edge  of  the  graduated 
Bide  of  the  declination  arc 
5 


66 


THE  SOLAR  COMPASS. 


The  axis  of  the  declination  arc,  or  indeed  the  whole  socket, 
Pj  is  appropriately  termed  the  polar  axis. 

The  Adjuster. — Besides  the  parts  shown  in  the  cut,  there 
is  also  an  arm  used  in  the  adjustment  of  the  instrument  as 
described  hereafter,  but  laid  aside  in  the  box  when  that  is 
effected. 

The  parts  just  described  constitute  properly  the  solar 
apparatus. 

Besides  these,  however,  are  seen  the  needle  box,  n,  with 
its  arc  and  tangent  screw,  ty  and  the  spirit  levels,  for  bringing 
the  whole  instrument  to  a  horizontal  position. 

The  Needle  Box,  n,  has  an  arc  of  about  36°  in  extent, 
divided  to  half  degrees,  and  figured  from  the  centre  or  zero 
mark  on  either  side. 

The  needle,  which  is  made  as  in  other  instruments,  except 
that  the  arms  are  of  unequal  lengths,  is  raised  or  lowered 
by  a  lever  shown  in  the  cut. 

The  needle  box  is  attached  by  a  projecting  arm  to  a  tan- 
gent screw,  t,  by  which  it  is  moved  about  its  centre,  and  its 
needle  set  to  any  variation. 

This  variation  is  also  read  off  by  the  vernier  on  the  end  of 
the  projecting  arm,  reading  to  single  minutes  a  graduated 
arc,  attached  to  the  plate  of  the  compass. 

The  Levels  seen  with  the  solar  apparatus,  have  ground 
glass  vials,  and  are  adjustable  at  their  ends  like  those  of  our 
other  instruments. 

The  edge  of  the  circular  plate  on  which  the  solar  work  is 
placed,  is  divided  and  figured  at  intervals  of  ten  degrees,  and 
numbered,  as  shown,  from  0  to  90  on  each  side  of  the  line  of 
sight. 

These  graduations  are  used  in  connection  with  a  little 
brass  pin,  seen  in, the  centre  of  the  plate,  to  obtain  approxi- 
mate bearings  of  lines,  which  are  not  important  enough  to 
require  a  close  observation. 


THE  SOLAR  COMPASS. 


67 


Lines  of  Kefraction. — The  inside  faces  of  the  sights  are 
also  graduated  and  figured,  to  indicate  the  amount  of  re- 
fraction to  be  allowed  when  the  sun  is  near  the  horizon. 
These  are  not  shown  in  the  cut. 

The  Horizontal  Limb  in  all  our  Solar  Compasses  is  divided 
upon  silver,  and  reads  by  two  opposite  verniers  to  single 
minutes  of  a  degree,  the  number  of  minutes  being  counted 
off  in  the  same  direction  in  which  the  vernier  moves. 
Definition  of  Astronomical  Terms, 

Before  proceeding  to  describe  the  principles  and  adjust- 
ments of  this  instrument,  a  brief  statement  of  the  terma 
employed  may  here  be  appropriately  made. 

The  Sun  is  the  centre  of  the  solar  system,  remaining  con- 
stantly fixed  in  its  position,  though,  for  the  sake  of  conve- 
nience, often  spoken  of  as  in  motion  around  the  earth. 

The  Earth  makes  a  complete  revolution  around  the  sun  in 
365  days,  6  hours,  very  nearly. 

It  also  rotates  about  an  imaginary  line  passing  through 
its  centre,  and  termed  its  axis^  once  in  twenty-four  hours, 
turning  from  west  to  east. 

The  Poles  are  the  extremities  of  the  axis  ;  that  in  our 
own  hemisphere,  known  as  the  north  pole,  if  produced  in- 
definitely towards  the  concave  surface  of  the  heavens,  would 
reach  a  point  situated  near  the  polar  star,  and  called  the 
north  pole  of  the  heavens. 

The  Equator  is  an  imaginary  line  passing  around  the  earth 
equi-distant  from  the  poles,  and  at  right  angles  with  them. 

If  the  plane  of  the  equator  is  produced  to  the  heavens,  it 
forms  what  is  termed  the  equator  of  the  heavens. 

The  Orbit  of  the  earth  is  the  path  in  which  it  moves  in 
making  its  yearly  revolution. 

If  the  plane  of  this  orbit  were  extended  to  the  heavens,  it 
would  form  the  ecliptic  or  the  sun's  apparent  path  in  the 
heavens. 


68 


THE  SOLAR  COMPASS. 


The  earth's  axis  is  inclined  to  its  orbit  at  an  angle  of 
about  23^  28',  making  the  angle  between  the  earth's  orbit 
and  its  equator,  or  between  the  celestial  equator  and  the 
ecliptic  of  the  same  amount. 

The  Equinoxes  are  the  two  points  in  which  the  ecliptic 
and  the  celestial  equator  intersect  each  other. 

The  Declination  of  the  sun  is  its  angular  distance  north 
or  south  of  the  celestial  equator  ;  when  the  sun  is  at  the 
equinoxes,  that  is  about  the  21st  of  March  and  the  21st  of 
September  of  each  year,  his  declination  is  0,  or  he  is  said  to 
be  on  the  equator;  from  these  points  his  declination  increases 
from  day  to  day,  and  from  hour  to  hour,  until,  on  the  21st  of 
Jane  and  21st  of  December,  he  is  23^  28'  distant  from  the 
equator. 

It  is  the  declination  which  causes  the  sun  to  appear  so 
much  higher  in  summer  than  in  v/inter,  his  altitude  in  the 
heavens  being  in  fact  nearly  4^^  more  on  the  21st  of  June 
than  it  is  on  the  21st  of  December. 

The  Horizon  of  a  place  is  the  surface  which  is  defined  by 
a  plane  supposed  to  pass  through  the  place  at  right  angles 
to  a  vertical  or  plumb  line,  and  to  bound  our  vision  at  the 
surface  of  the  earth. 

The  horizon  or  a  horizontal  surface  is  determined  by  the 
surface  of  any  liquid  when  at  rest,  or  by  the  spirit  levels  of 
an  instrument. 

The  Zenith  of  any  place  is  the  point  directly  over  head, 
at  right  angles  to  the  horizon. 

The  Meridian  of  any  place  is  a  great  circle  passing  through 
the  zenith  of  a  place,  and  the  poles  of  the  earth. 

The  meridian,  or  true  north  and  south  line  of  any  place  is 
the  line  determined  by  the  intersection  of  the  plane  of  the 
meridian  circle  with  the  plane  of  the  horizon. 

The  Meridian  Altitude  of  the  sun  is  its  angular  elevation 
^hifvn  the  horizon,  when  passing  the  meridian  of  a  place. 


THE  SOLAR  COMPASS. 


69 


The  Latitude  of  a  place  is  its  distance  north  or  south  of 
the  equator,  measured  on  a  meridian.  At  the  equator  the 
latitude  is  0^,  at  the  poPes  90^. 

The  Longitude  of  a  place  is  its  distance  in  degrees  or  in 
time,  east  or  west  of  a  given  place  taken  as  the  starting 
point  or  first  meridian;  it  is  measured  on  the  equator  or  any 
parallel  of  latitude. 

In  the  Nautical  Almanac,  which  is  commonly  used  with 
the  Solar  Compass,  the  longitude  of  the  principal  places  in 
the  United  States  is  reckoned  from  Greenwich,  England,  and 
expressed  both  in  degrees  and  hours. 

The  Zenith  Distance  of  any  heavenly  body,  is  its  angular 
distance  north  or  south  of  the  zenith  of  a  place,  measured 
when  the  body  is  on  the  meridian. 

Suppose  a  person  situated  on  the  equator  at  the  time  of 
the  equinoxes,  the  sun,  when  on  the  meridian,  would  be  in 
the  zenith  of  the  place,  and  the  poles  of  the  earth  would,  of 
course,  lie  in  the  plane  of  his  horizon. 

Disregarding  for  the  present  the  declination  of  the  sun, 
let  us  suppose  the  person  travels  towards  the  north  pole. 

As  he  passes  to  the  north,  the  sun  will  descend  from  the 
zenith,  and  the  pole  rise  from  the  horizon  in  the  same  propor- 
tion, until  when  he  arrives  at  the  north  pole  of  the  earth, 
the  sun  will  have  declined  to  the  horizon,  and  the  pole  of  the 
heavens  will  have  reached  the  zenith. 

The  altitude  of  the  pole  at  any  place,  or  the  distance  of 
the  sun  from  the  zenith,  would  in  the  case  supposed,  give 
the  observer  the  latitude  of  that  place. 

If  we  now  take  into  account  the  sun's  declination,  it  would 
increase  or  diminish  its  meridian  altitude,  according  as  it 
passes  north  or  south  of  the  equator  ;  but  the  declination  of 
the  sun  at  any  time  being  known,  its  zenith  distance,  and 
therefore  the  latitude  of  the  place,  can  be  readily  ascertained 
by  an  observation  made  when  it  is  on  the  meridian. 


70 


THE  SOLAR  COMPASS. 


As  we  shall  see  hereafter,  it  is  by  this  method  that  we 
obtain  the  latitude  of  any  place  by  the  Solar  Compass. 

Time. — A  solar  day*  is  the  interval  of  time  between  the 
departure  of  the  sun  from  the  meridian  of  a  place,  and  its 
succeeding  return  to  the  same  position. 

The  length  of  the  solar  day,  by  reason  of  the  varying 
velocities  of  the  earth  in  its  orbit,  and  the  inclination  of  its 
axis,  is  continually  changing. 

In  order  to  have  a  uniform  measure  of  time,  we  have 
recourse  to  what  is  termed  a  mean  solar  day^  the  length  of 
which  is  equal  to  the  mean  or  average  of  all  the  solar  days 
in  a  year. 

The  time  thus  given  is  termed  mean  time^  and  is  that  to 
which  clocks  and  watches  are  adjusted  for  the  ordinary 
business  of  life. 

The  sun  is  sometimes  faster,  and  sometimes  slower,  than 
the  clock,  the  difference  being  termed  the  equation  of  time. 

The  moment  when  the  sun  is  on  the  meridian  of  any  place 
is  termed  apparent  noon,  and  this  being  ascertained,  we  can, 
by  referring  to  the  equation  of  time  for  the  given  day,  and 
adding  to,  or  subtracting  from,  apparent  noon,  according 
as  the  sun  is  slow  or  fast,  obtain  the  time  of  mean  noon,  by 
which  to  set  the  watch  or  chronometer. 

Difference  of  Longitude. — As  the  earth  makes  a  complete 
rotation  upon  its  axis  once  a  day,  every  point  on  its  surface 
must  past  over  360°  in  24  hours,  or  15^  in  one  hour,  and  so 
on  in  the  same  proportion. 

And  as  the  rotation  is  from  west  to  east,  the  sun  would 
come  to  the  meridian  of  every  place  15^  west  of  Greenwich, 
just  one  hour  later  than  the  time  given  in  the  Almanac,  for 
apparent  noon  at  that  place. 

To  an  observer  situated  at  Troy,  N.  Y.,  the  longitude  of 
which  is  in  time  4  hours  54  minutes,  40  sec,  the  sun  would 
come  to  the  meridian  nearly  five  hours  later  than  at  Green^ 


THE  SOLAB  COMPASS. 


71 


wich,  and  thus  when  it  was  12  M.  at  that  place,  it  would  be 
be  but  about  1  o'clock  A.  M.  in  Troy. 

Refraction. — By  reason  of  -the  increasing  density  of  the 
atmosphere  from  its  upper  regions  to  the  earth's  surface,  the 
rays  of  light  from  the  sun  are  bent  out  of  their  course,  so  as 
to  make  his  altitude  appear  greater  than  is  actually  the  case. 

The  amount  of  refraction  varies,  according  to  the  altitude 
of  the  body  observed  ;  being  0  when  it  is  in  the  zenith, 
about  one  minute  when  midway  from  the  horizon  to  the 
zenith,  and  almost  34'  when  in  the  horizon. 

To  indicate  the  amount  of  refraction  to  be  allowed  in 
observations  with  the  solar  compass,  the  sights  have  on 
their  inside  faces  a  number  of  lines,  marked  at  intervals, 
and  figured  so  as  to  read  off  the  degree  of  refraction  of  the 
sun  or  other  body,  when  seen  directly  over  the  top  of  one 
sight,  by  the  eye  placed  on  the  other  at  the  height  marked 
by  the  line  of  refraction. 

Effect  of  Incidental  Refraction. — It  will  be  seen  by 
referring  to  the  instrument,  that  the  effect  of  the  ordinary 
refraction,  which  to  distinguish  from  meridional  refraction, 
we  will  term  incidental,  upon  the  position  of  the  sun's  image 
with  reference  to  the  equatorial  lines,  which,  in  fact,  are  the 
only  ones  to  be  regarded  in  running  lines  with  the  Solar 
Compass,  is  continually  changing,  not  only  with  the  change 
of  latitude,  but  also  with  that  of  the  sun's  declination  from 
hour  to  hour,  and  the  motion  of  the  revolving  arm  as  it  fol- 
lows the  sun  in  its  daily  revolution. 

If  the  equatorial  lines  were  always  in  the  same  vertical 
plane  with  the  sun,  as  would  be  the  case  at  the  equator  at 
the  of  the  equinoxes,  it  is  evident  that  refraction  would 
have  no  effect  upon  the  position  of  the  image  between  these 
lines,  and  therefore  would  not  be  of  any  importance  to  the 
surveyor. 

But  as  we  proceed  further  north,  and  as  the  sun's  declina* 


72 


THE  SOLAR  COMPASS. 


tion  to  the  south  increases,  the  refraction  also  increases,  and 
must  now  be  taken  into  account. 

Again  the  angle  which  the  equatorial  lines  make  with  the 
horizon  is  continually  changing  as  the  arm  is  made  to  follow 
the  motion  of  the  sun  during  the  course  of  a  day. 

Thus  in  the  morning  and  evening  they  are  more  or  less 
inclined  to  the  horizon,  while  at  noon  they  are  exactly 
parallel  to  it. 

And  thus  it  follows  that  the  excess  of  refraction  at  morn» 
ing  and  evening  is  in  some  measure  balanced  by  the  fact 
that  the  position  of  the  sun's  image  with  reference  to  the 
equatorial  lines  is  then  less  affected  by  it,  on  account  of  the 
greater  inclination  of  the  lines  to  the  horizon. 

Besides  the  causes  already  mentioned  as  modifying  the 
effect  of  refraction,  we  may  add  that  of  the  numerous  changes 
in  the  atmosphere  ;  and  when  all  these  are  considered,  it 
will  be  seen  that  any  idea  of  calculating  the  amount  and 
influence  of  refraction  with  certainty  may  well  be  abandoned. 

The  best  than  can  be  done,  is  to  estimate  and  allow  for  it 
as  a  little  experience  will  suggest  during  morning  and 
evening,  and  disregard  it  entirely  for  the  rest  of  the  day. 

We  shall  give  the  practice  of  government  surveyors  in 
allowing  for  refraction,  when  we  come  to  speak  of  the  man- 
ner in  which  the  Solar  Compass  is  used. 

The  Meridional  Refraction  of  the  sun  is  that  by  which 
his  position  is  affected  when  on  the  meridian. 

It  varies  of  course,  with  the  varying  meridional  altitudes 
of  the  sun,  and  in  all  places  in  north  latitude  must  be  added 
to  the  declination  when  it  is  north,  and  subtracted  when  it  is 
south,  in  order  to  obtain  the  true  declination  for  the  given  day. 

This  is  done  for  the  starting  hour  as  will  be  hereafter 
described,  and  is  carried  through  the  other  hours  of  the  day 
without  further  addition. 

To  obtain  the  meridional  refraction  of  the  sun  for  a  given 


THE  SOLAR  COMPASS. 


73 


day  and  place,  we  first  ascertain  the  meridional  altitude  of 
the  sun  on  that  day,  and  then  refer  to  the  table  of  refractions 
given  in  the  Almanac  a  few  pages  beyond  the  ephemeris 
of  the  sun,  and  find  the  amount  of  refraction  corresponding 
to  the  angle  thus  obtained,  which  will  be  the  meridional 
refraction  required. 

Thus  to  obtain  the  meridional  refraction  of  the  sun  for 
April  16th,  1868,  at  Troy,  N.  Y.,  proceed  as  follows  : 

Latitude  of  Troy  .42^  W 

90—42^^  44'=4r  16' 
Declination  April  16,  which  is  north  or  -f-   10°  19'  22' 

Gives  a  meridional  altitude  of     57°  35'  22^' 
Referring  now  to  the  table  of  refractions  we  find  the  amount 

corresponding  to  the  angle  thus  found  to  be  38^',  which  is  the 

meridional  refraction  for  the  given  day,  and  is  to  be  added 

to  the  declination,  as  will  hereafter  be  seen. 

Again,  let  it  be  required  to  obtain  the  meridional  refraction 

at  the  same  place,  Oct.  15,  1868,  the  declination  now  being 

in  the  contrary  direction. 

Latitude  of  Troy  42°  44' 

90—42°  44'=4T°  16' 

Declination  for  Oct.  16,  which  is  south  or  —  • .  • .     9°    5'  40'' 

Gives  a  meridional  altitude  of     38°  10'  20" 
Eeferring  again  to  the  table,  we  find  the  refraction  for  the 
meridional  altitude  just  found  to  be  1'  14",  which  is  now  to 
be  subtracted  from  the  declination  for  the  given  day,  when 
it  is  set  off  upon  the  declination  arc. 

As  will  be  seen  by  both  examples,  the  meridional  refraction, 

though  affecting  the  sun's  declination  by  a  constant  quantity 
through  the  whole  day,  is  yet  of  comparatively  small  amount, 
and  in  practice  is  often  entirely  disregarded,  except  by  those 
surveyors  engaged  in  running  the  great  standard  meridians 
and  parallels  of  latitude,  or  in  testing  their  instruments. 


74 


THE  SOLAR  COMPASS. 


Principles  of  the  Solar  Compass. 
We  are  now  prepared,  to  proceed  to  the  explanation  of  the 
peculiar  construction  of  the  instrument  we  are  considering. 

The  little  silver  plate  before  referred  to,  is  shown  in  detail 
in  fig.  13.    On  its  surface  are  marked  two  sets  of  lines  inter- 
Fig.  13.         secting  each  other  at  right  angles;  of  these, 
b  b  are  termed  the  hour  lines,  and  c  c  the 
equatorial  lines,  as  having  reference  respec- 
tively, to  the  hour  of  the  day  and  the  posi- 
tion of  the  sun,  in  relation  to  the  equator. 
Below  the  equatorial  lines  are  also  marked  three  other  lines, 
which  are  five  minutes  apart,  and  are  of  service  in  making 
allowance  for  refraction,  as  will  be  hereafter  explained. 

The  interval  between  the  two  lines  c,  c,  as  well  as  between 
6,  6,  is  just  sufficient  to  include  the  circular  image  of  the  sun, 
as  formed  by  the  solar  lens,  on  the  opposite  end  of  the  re- 
volving arm. 

When,  therefore,  the  instrument  is  made  perfectly  hori- 
zontal, the  equatorial  lines  and  the  opposite  lenses  being 
accurately  adjusted  to  each  other  by  a  previous  operation, 
and  the  sun^s  image  brought  within  the  equatorial  lines,  his 
position  in  the  heavens,  with  reference  to  the  horizon,  will 
be  defined  with  precision. 

Suppo»D  the  observation  to  be  made  at  the  time  of  one  of 
the  equinoxes  ;  the  arm  set  at  zero  on  the  declination  arc 
b,  and  the  polar  axis  placed  exactly  parallel  to  the  axis  of 
the  earth. 

Then  the  motion  of  the  arm  h,  if  revolved  on  the  spindle 
of  the  declination  arc  around  the  hour  circle  c,  will  exactly 
correspond  with  the  motion  of  the  sun  in  the  heavens,  on  the 
given  day  and  at  the  place  of  observation  ;  so  that  if  the 
sun's  image  was  brought  between  the  lines  c  c,  in  the  morn- 
ing, it  would  continue  in  the  same  position,  passing  neither 


0  \ 

^1 

THE  SOLAR  COMPAaS. 


75 


above  nor  helow  the  lines,  as  the  arm  was  made  to  revolve 
in  imitation  of  the  motion  of  the  sun  about  the  earth. 

In  the  morning  as  the  sun  rises  from  the  horizon,  the  arm 
h  will  be  in  a  position  nearly  at  right  angles  to  that  shown 
in  the  cut,  the  lens  being  turned  towards  the  sun,  and  the 
silver  plate  on  which  his  image  is  thrown  directly  opposite. 

As  the  sun  ascends,  the  arm  must  be  moved  around,  until 
when  he  has  reached  the  meridian,  the  graduated  side  of  the 
declination  arc  will  indicate  12  on  the  hour  circle,  and  the  arm 
hj  the  declination  arc  6,  and  the  latitude  arc  a,  will  be  in  the 
same  plane. 

As  the  sun  declines  from  the  meridian  the  arm  h  must  be 
moved  in  the  same  direction,  until  at  sunset  its  position  will 
be  the  exact  reverse  of  that  it  occupied  in  the  morning. 

Allowance  for  Declination. — Let  us  now  suppose  the 
observation  made  when  the  sun  has  passed  the  equinoctial 
point,  and  when  his  position  is  affected  by  declination. 

By  referring  to  the  Almanac,  and  setting  off  on  the  arc 
his  declination  for  the  given  day  and  hour,  we  are  still  able 
to  determine  his  position  with  the  same  certainty  as  if  he 
remained  on  the  equator. 

When  the  sun's  declination  is  south,  that  is  from  the  2 2d 
of  September  to  the  20th  of  March  in  each  year,  the  arc  b  is 
turned  towards  the  plates  of  the  compass,  as  shown  in  the 
engraving,  and  the  solar  lens,  o,  with  the  silver  plate  oppo- 
site, are  made  use  of  in  the  surveys. 

The  remainder  of  the  year,  the  arc  is  turned  from  the 
plates,  and  the  other  lens  and  plate  employed. 

When  the  Solar  Compass  is  accurately  adjusted,  and  its 
plates  made  perfectly  horizontal,  the  latitude  of  the  place, 
and  the  declination  of  the  sun  for  the  given  day  and  hour, 
being  also  set  off  on  the  respective  arcs,  the  image  of  the 
sun  cannot  be  brought  between  the  equatorial  lines  until  the 
polar  axis  is  placed  in  the  plane  of  the  meridian  of  the  place ^  or 


76 


THE  SOLAR  COMPASS. 


in  a  prrfHon  parallel  to  the  axis  of  the  earth  The  slightest 
deviatio?!  from  this  position  will  cause  the  image  to  pass 
ubove  or  below  the  lines,  and  thus  discover  the  erroi. 

We  thus,  from  the  position  of  the  sun  in  the  solai  system, 
obtain  a  certain  direction  absolutely  unchangeable,  from  which 
to  run  our  lines,  and  measure  the  horizontal  angles  required. 

This  simple  principle  is  not  only  the  basis  of  the  construc- 
tion of  the  Solar  Compass,  but  the  sole  cause  of  its  superiority 
to  the  ordinary  or  magnetic  instrument.  For  in  a  needle 
instrument,  as  before  stated  in  this  work,  the  accuracy  of 
the  horizontal  angles  indicated,  and  therefore  of  all  the 
observations  made,  depends  upon  the  delicacy  of  the  needle, 
and  the  constancy  with  which  it  assumes  a  certain  direction, 
termed  the  magnetic  meridian.'' 

The  principal  causes  of  error  in  the  needle  as  briefly 
stated,  are  the  dulling  of  the  pivot,  the  loss  of  polarity  in 
the  needle,  the  influence  of  local  attraction,  and  the  effect  of 
the  sun's  rays,  producing  the  diurnal  variation. 

From  all  these  imperfections  the  solar  instrun^ent  is  free. 

The  sights  and  the  graduated  limb  being  adjusted  to  the  solar 
apparatus,  and  the  latitude  of  the  place,  and  the  declination 
of  the  sun  also  set  off  upon  the  respective  arcs,  we  are 
able,  not  only  to  run  the  true  meridian,  or  a  due  east  and 
west  course,  but  also  to  set  off  the  horizontal  angles  with 
minuteness  and  accuracy  from  a  direction  which  never 
changes,  and  is  unaffected  by  attraction  of  any  kind. 

To  adjust  the  Solar  Compass. 

The  adjustments  of  this  instrument,  with  which  the  sur- 
veyor will  have  to  do,  are  simple  and  few  in  number,  and 
will  now  be  given  in  order. 

1st,  To  Adjust  the  Levels. — Proceed  precisely  as  directed 
in  the  account  of  the  other  instruments  we  have  described, 
by  bringing  the  bubbles  into  the  centre  of  the  tubes  by  the 
leveling  screws  of  the  tripod,  and  then  reversing  the  instru- 


THE  SOLAR  COMPASS- 


77 


ment  upon  its  spindle,  and  raising  or  lowering  the  ends  of 
the  tubes,  until  the  bubbles  will  remain  in  the  centre  during 
a  complete  revolution  of  the  instrument. 

2d,  To  Adjust  the  Equatorial  Lines  and  Solar  Lenses.— 
First  detach  the  arm  h  from  the  declination  arc  by  withdraw- 
ing the  screws  shown  in  the  cut  from  the  ends  of  the  posts 
of  the  tangent  screw,  ^,  and  also  the  clamp  screw,  and  the 
conical  pivot  with  its  small  screws  by  which  the  arm  and 
declination  arc  are  connected. 

The  arm,  7i,  being  thus  removed,  attach  the  adjuster  in  its 
place  by  replacing  the  conical  pivot  and  screws,  and  insert 
the  clamp  screw  so  as  to  clamp  the  adjuster  at  any  point  on 
the  declination  arc. 

Now  level  the  instrument,  place  the  arm  h  on  the  adjuster, 
with  the  same  side  resting  against  the  surface  of  the  decli- 
nation arc  as  before  it  was  detached.  Turn  the  instrument 
on  its  spindle  so  as  to  bring  the  solar  lens  to  be  adjusted  in 
the  direction  of  the  sun,  and  raise  or  lower  the  adjuster  on 
the  declination  arc,  until  it  can  be  clamped  in  such  a  posi- 
tion, as  to  bring  the  sun's  image  as  near  as  may  be  between 
the  equatorial  lines  on  the  opposite  silver  plate,  and  bring 
the  image  precisely  into  position,  by  the  tangent  of  the  lati- 
tude arc,  or  the  leveling  screws  of  the  tripod.  Then  care- 
fully turn  the  arm  half  way  over,  until  it  rests  upon  the 
adjuster  by  the  opposite  faces  of  the  rectangular  blocks,  and 
again  observe  the  position  of  the  sun's  image. 

If  it  remains  between  the  lines  as  before,  the  lens  and 
plate  are  in  adjustment ;  if  not,  loosen  the  three  screws 
which  confine  the  plate  to  the  block,  and  move  the  plato 
under  their  heads,  until  one  half  the  error  in  the  position  of 
the  sun's  image  is  removed. 

Again  bring  the  image  between  the  lines,  and  repeat  the 
operation  until  it  will  remain  in  the  same  situation,  in  both 
positions  of  the  arm,  when  the  adjustment  will  be  completed 


78 


THE  SOLAR  COMPASS. 


To  adjust  the  other  lens  and  plate,  reverse  the  arm  end  for 
end  on  the  adjuster,  and  proceed  precisely  as  in  the  former 
case,  until  the  same  result  is  attained. 

In  tightening  the  screws  over  the  silver  plate,  care  must 
be  taken  not  to  move  the  plate. 

This  adjustment  now  being  complete,  the  adjuster  should 
be  removed,  and  the  arm,  h,  with  its  attachments,  replaced 
as  before. 

3d,  To  Adjust  the  Vernier  of  the  Declination  Arc. — 
Having  leveled  the  instrument,  and  turned  its  lens  in  the 
direction  of  the  sun,  clamp  to  the  spindle,  and  set  the  ver- 
nier, V,  of  the  declination  arc,  at  zero,  by  means  of  the  tan- 
gent screw,  at  k,  and  clamp  to  the  arc. 

See  that  the  spindle  moves  easily  and  yet  truly  in  the 
socket,  or  polar  axis,  and  raise  or  lower  the  latitude  arc 
by  turning  the  tangent  screw,  /,  until  the  sun's  image  is 
brought  between  the  equatorial  lines  on  one  of  the  plates. 
Clamp  the  latitude  arc  by  the  screw,  and  bring  the  image 
precisely  into  position  by  the  leveling  screws  of  the  tripod 
or  socket,  and  without  disturbing  the  instrument,  carefully 
revolve  the  arm  hy  until  the  opposite  lens  and  plate  are 
brought  in  the  direction  of  the  sun,  and  note  if  the  sun's 
image  comes  between  the  lines  as  before. 

If  it  does,  there  is  no  index  error  of  the  declination  arc ; 
if  not  with  the  tangent  screw,  move  the  arm  until  the 
sun's  image  passes  over  half  the  error;  again  bring  the  image 
between  the  lines,  and  repeat  the  operation  as  before,  until 
the  image  will  occupy  the  same  position  on  both  the  plates. 

We  shall  now  find,  however,  that  the  zero  marks  on  the 
arc  and  the  vernier  do  not  correspond,  and  to  remedy  this 
error,  the  little  flat  head  screws  above  the  vernier  must  be 
loosened  until  it  can  be  moved  so  as  to  make  the  zeros 
coincide,  when  the  operation  will  be  completed. 


THE  SOLAR  COMPASS. 


79 


4th,  To  Adjust  the  Solar  Apparatus  to  the  Compass 
Sights. — First  level  the  instrument,  and  with  the  clamp  and 
tangent  screws  set  the  main  plate  at  90°  by  the  verniers 
and  horizontal  limb.  Then  remove  the  clamp  screw,  and 
raise  the  latitude  arc  until  the  polar  axis  is  by  estimation 
very  nearly  horizontal,  and  if  necessary,  tighten  the  screws 
on  the  pivots  of  the  arc,  so  as  to  retain  it  in  this  position. 

Fix  the  vernier  of  the  declination  arc  at  zero,  and  direct 
the  equatorial  sights  to  some  distant  and  well  marked  object, 
and  observe  the  same  through  the  compass  sights.  If  the 
same  object  is  seen  through  both,  and  the  verniers  read  to 
90°  on  the  limb,  the  adjustment  is  complete  ;  if  not,  the  cor- 
rection must  be  made  by  moving  the  sights  or  changing  the 
position  of  cYiks  verniers. 

In  that  form  of  this  instrument,  described  hereafter  as  the 
Solar  Compass  proper,  the  solar  work  is  attached  perma- 
nently to  the  sockets,  and  this  adjustment  once  made  by  the 
maker,  will  need  no  further  attention  at  the  hands  of  the 
surveyor,  unless  in  case  of  severe  accidents. 

In  the  second  form,  termed  the  Solar  Telescope  Compass, 
the  socket  of  the  telescope  is  made  so  as  to  be  adjustable 
horizontally,  and  thus  set  to  the  solar  apparatus  and  divided 
limb  with  certainty  and  ease. 

Other  Adjustments. — We  should  perhaps  here  say,  that 
the  above  adjustments,  as  well  as  the  others  with  which  the 
surveyor  ordinarily  will  have  no  concern,  are  all  made  by 
us,  in  the  process  of  constructing  and  finishing  our  instru- 
ments, and  are  liable  to  very  little  derangement  in  the  ordi- 
nary use  of  the  Solar  Compass. 

Tripods,  Sc. 

The  Solar  Compass  should  always  be  used  on  a  tripod  pro- 
vided with  some  means  by  which  it  may  be  leveled  with  ease 
and  accuracy. 

A  tangent  motion  to  the  whole  instrument  about  its  spindle, 


80  THE  SOLAR  COMPASS. 

in  addition  to  tliat  of  the  limb  already  spoken  of,  is  also  of 
very  great  value. 

These  requirements  are,  we  think,  best  supplied  in  our 
Adjusting  Socket,  with  compound  tangent  ball,  shown  in 
fig.  14,  being  screwed  into  the  top  of  a  tripod  like  the  ordi- 
nary leveling  head. 

The  interior  stem  of  the  socket  is  expanded  above  to 
receive  the  ball  of  the  compass,  and  below,  pivots  upon  a 
small  ball  confined  underneath  the  plate  of  the  tripod. 

The  instrument  is  approximately  leveled  by  the  ball  and 
socket  joint,  and  finally  made  perfectly  horizontal  by  the 
leveling  screws  of  the  socket. 

It  also  revolves  upon  the  spindle  as 
upon  the  ordinary  compass  ball,  but  can 
be  clamped  at  pleasure  to  the  spindle, 
and  then  by  its  sights  or  telescope 
directed  precisely  to  any  object  by  the 
tangent  screw  of  the  compound  ball. 

The  ordinary  adjusting  tripod  head 
with  leveling  screws,  and  clamp  and 
tangent  movement,  as  shown  with  our 
Surveyor's  Transit,  is  also  used  with 
this  instrument,  but  is  heavier  and  less 
capable  of  rapid  adjustment. 

Of  course  when  a  single  or  jacob  staff 
is  preferred  to  the  tripod,  for  this  or  any 
other  of  our  compasses,  the  adjusting 
socket,  with  either  a  simple  or  compound 
ball,  can  be  placed  upon  the  top  of  the 
staff  and  adjusted  as  just  described. 
In  all  cases  where  either  a  leveling  tripod  or  the  adjust- 
ing socket,  with  compound  ball,  is  furnished  with  this 
instrument,  a  simple  ball  is  also  supplied,  upon  which  the 
compass  can  be  placed  whenever  desired. 


THE  SOLAR  COMPASS. 


81 


The  simple  ball  is  furnished  with  an  extra  cap  for  the 
socket,  or  in  case  of  the  leveling  tripod,  with  an  adopter, 
fitting  to  the  top  of  the  tripod,  so  that  the  substitution  can 
be  made  by  the  surveyor  himself  without  any  difficulty. 

Prices  of  the  Socket. — As  the  adjusting  socket  may  often 
be  used  to  advantage  with  the  other  instruments  described 
in  this  work,  we  will  here  insert  its  prices  with  its  various 
modifications. 

With  tripod  and  compound  ball  as  in  fig.  14  .  .$18  00 

simple    12  00 

"    Jacob  staff  and  compound  ball   12  00 

simple    6  00 

To  use  the  Solar  Compass. 

Before  this  instrument  can  be  used  at  any  given  place  it  is 
necessary  to  set  off  upon  its  arcs  both  the  declination  of  the 
sun  as  affected  by  its  meridional  refraction  for  the  given  day, 
and  the  latitude  of  the  place  where  the  observation  is  made. 

To  SET  OFF  THE  DECLINATION. — The  dcclination  of  the  sun, 
given  in  the  Ephemeris  of  the  Nautical  Almanac,  from  year  to 
year,  is  calculated  for  apparent  noon  at  Greenwich,  England. 

To  determine  it  for  any  other  hour  at  a  place  in  the  U.  S., 
reference  must  be  had,  not  only  to  the  difference  of  time 
arising  from  the  longitude,  but  also  to  the  change  of  declina- 
tion from  day  to  day. 

The  longitude  of  the  place,  and  therefore  its  difference  in 
time,  if  not  given  directly  in  the  tables  of  the  Almanac,  can 
be  ascertained  very  nearly  by  reference  to  that  of  other 
places  given,  which  are  situated  on,  or  very-  nearly  on,  the 
same  meridian. 

It  is  the  practice  of  surveyors  in  the  States  east  of  the 
Mississippi  to  allow  a  difference  of  six  hours  for  the  difference 
in  longitude,  calling  the  declination  given  in  the  Almanac 
for  ]  2  M.,  that  of  6  A.  M.,  at  the  place  of  observation. 


6 


82 


THE  SOLAR  COMPASS. 


Beyond  the  parallel  of  Santa  Fe,  the  allowance  would  be 
about  seven  hours,  and  in  California,  Oregon,  and  Washing- 
ton Territory  about  eight  hours. 

Having-  thus  the  difference  of  time,  we  very  readily  obtain 
the  declination  for  a  certain  hour  in  the  morning,  which 
would  be  earlier  or  later  as  the  longitude  was  greater  or  less, 
and  the  same  as  that  of  apparent  noon  at  Greenwich  on  the 
given  day.  Thus  suppose  the  observation  made  at  a  place, 
say,  five  hours  later  than  Greenwich,  then  the  declination 
given  in  the  Almanac  for  the  given  day  at  noon,  affected  by 
the  meridional  refraction,  would  be  the  declination  at  the 
place  of  observation  for  7  o'clock,  A.  M.;  this  gives  us  the 
starting  point. 

To  obtain  the  declination  for  the  other  hours  of  the  day 
take  from  the  Almanac,  the  declination  for  apparent  noon  of 
the  given  day,  and  also  that  of  the  day  following,  subtract 
one  from  the  other,  as  it  may  have  increased  or  decreased, 
and  we  have  the  change  of  declination  for  24  hours,  divide 
this  by  24,  and  we  obtain  the  change  of  declination  for  a 
Bingle  hour,  which  is  to  be  added  to,  or  subtracted  from 
that  of  the  starting  hour,  according  as  the  declination  is 
increasing  or  decreasing  between  the  two  days  taken. 

To  make  this  more  plain  we  will  give  an  example.  Sup- 
pose it  was  required  to  obtain  the  declination  for  the  dif- 
ferent hours  of  April  16th,  1868,  at  Troy,  N.  Y. 

The  longitude  in  time  is  4  hrs.  54  min.  40  sec,  or  practi- 
cally 5  hours,  so  that  the  declination  given  in  the  Almanac 
For  the  given  day  at  Greenwich  would  be  that  of  t  A.  M.  at 
Troy. 

To  obtain  the  hourly  change. 
Say  declination  at  Greenwich,  April  17.  .10**  40'  28" 

16.. 10    19  22 


Change  for  24  hours 


21  06 


THE  SOLAR  COMPASS.  83 

Reduce  to  seconds,  and  divide  by  24,  and  we  have  an  hourly 
change  of  50  seconds,  which,  as  the  declination  is  increasing, 
is  to  be  added  every  hour  after  7  A.  M. 

Ilence,  sun's  declination  at  Greenwich  noon  as  by  the  table 


,10° 

19' 

22" 

Add  meridional  refraction . 

38 

10 

20 

:Dec. 

for  7  A.  M.. 

50~ 

10 

on 

OU 

O  " 

50 

10 

50 

10 

90 

i( 

50 

10 

23 

20 

({ 

11  " 

U  U 

10 

24 

10 

i( 

12  M. 

>  • 

10 

25 

(( 

1  P.  M 

a  (« 

50 

10 

25 

50 

( ( 

2  " 

a  (i 

50 

10 

26 

40 

(( 

3 

U  II 

50 

10 

27 

30 

a 

4  " 

ii  M 

50 

10 

28 

20 

(( 

6 

84 


THE  SOLAR  COMPASS. 


10°  28'  20'':=Dec.for5P.M, 

Add  hourly  change   50 

10    29    10  6  " 

"  "    50 

10    30  "       7  " 

In  the  case  taken  the  declination  is  increasing  from  day  to 
day,  and  therefore  the  hourly  change  is  added;  if,  on  the 
contrary,  the  declination  was  decreasing,  the  hourly  change 
should  be  subtracted. 

The  calculation  of  the  declination  for  the  different  hours  of 
the  day,  should  of  course  be  made  and  noted  before  the  sur- 
veyor commences  his  work,  that  he  may  lay  off  the  change 
from  hour  to  hour,  from  a  table  prepared  as  above  described. 

It  is  considered  sufficiently  accurate  by  most  government 
surveyors,  to  set  off  the  declination  only  three  or  four  times 
in  the  day,  at  intervals  of  two  or  three  hours  as  required. 

To  SET  OFF  THE  LATITUDE. — Find  the  declination  of  the  sun 
for  the  given  day  at  noon,  at  the  place  of  observation  as  just 
described,  and  with  the  tangent  screw  set  it  off  upon  the  de- 
clination arc,  and  clamp  the  arm  firmly  to  the  arc. 

Observe  in  the  almanac  the  equation  of  time  for  the  given 
day,  in  order  to  know  about  the  time  the  sun  will  reach  the 
meridian. 

Then,  about  fifteen  or  twenty  minutes  before  this  time,  set 
up  the  instrument,  level  it  carefully,  fix  the  divided  surface 
of  the  declination  arc  at  12  on  the  hour  circle,  and  turn  the 
instrument  upon  its  spindle  until  the  solar  lens  is  brought 
into  the  direction  of  the  sun. 

Loosen  the  clamp  screw  of  the  latitude  arc,  and  with  the 
tangent  crew  raise  or  lower  this  arc  until  the  image  of  the 
Bun  is  brought  precisely  between  the  equatorial  lines,  and 
turn  the  instrument  from  time  to  time  so  as  to  keep  the 
image  also  between  the  hour  lines  on  the  plate. 


THE  SOLAK  COMPASS. 


85 


As  the  sun  ascends,  its  image  will  move  below  the  lines, 
and  the  arc  must  be  moved  to  follow  it.  Continue  thus  keep- 
ing it  between  the  two  sets  of  lines  until  its  image  begins 
to  pass  above  the  equatorial  lines,  which  is  also  the  moment 
of  its  passing  the  meridian. 

Now  read  off  the  vernier  of  the  arc,  and  we  have  the  lati- 
tude of  the  place,  which  is  always  to  be  set  off  on  the  arc 
when  the  compass  is  used  at  the  given  place. 

It  is  the  practice  of  surveyors  using  the  Solar  Compass  to 
set  off,  in  the  manner  just  described,  the  latitude  of  the  point 
where  the  survey  begins,  and  to  repeat  the  observation  and 
correction  of  the  latitude  arc  every  day  when  the  weather  is 
favorable,  there  being  also  nearly  afi  hour  at  mid-day  when 
the  sun  is  so  near  the  meridian  as  not  to  give  the  direction 
of  lines  with  the  certainty  required. 

To  Run  Lines  with  the  Solar  Compass. — Having  set  off 
in  the  manner  just  given  the  latitude  and  declination  upon 
their  respective  arcs,  the  instrument  being  also  in  adjust- 
ment, the  surveyor  is  ready  to  run  lines  by  the  sun. 

To  do  this,  the  instrument  is  set  over  the  station  and 
carefully  leveled,  the  plates  clamped  at  zero  on  the  horizontal 
limb,  and  the  sights  directed  north  and  south,  the  direction 
being  given,  when  unknown,  approximately  by  the  needle. 

The  solar  lens  is  then  turned  to  the  sun,  and  with  one  hand 
on  the  instrument,  and  the  other  on  the  revolving  arm,  both 
are  moved  from  side  to  side,  until  the  sun's  image  is  made 
to  appear  on  the  silver  plate  ;  when  by  carefully  continuing 
the  operation,  it  may  be  brought  precisely  between  the 
equatorial  lines. 

Allowance  being  now  made  for  refraction,  the  line  of  sights 
will  indicate  the  true  meridian;  the  observation  may  now  be 
made,  and  the  flag-man  put  in  position. 

When  a  due  east  and  west  line  is  to  be  run,  the  verniers 


86 


THE  SOLAR  COMPASS. 


of  the  horizontal  limb  are  set  at  90^,  and  the  snn^s  image 
kept  between  the  lines  as  before. 

The  Solar  Compass  being  so  constructed  that  when  the 
sun's  image  is  in  position  the  limb  must  be  clamped  at  0  in 
order  to  run  a  true  meridian  line,  it  will  be  evident  that  the 
bearing  of  any  line  from  the  meridian,  may  be  read  by  the 
verniers  of  the  limb  precisely  as  in  the  ordinary  magnetic 
compass,  the  bearing  of  lines  are  read  from  the  ends  of  the 
needle. 

Allowance  for  Eefraction. — From  what  has  been  before 
stated,  it  will  be  seen  that  no  precise  calculation  can  be 
made  for  the  effect  of  incidental  refraction. 

The  practice  of  -  the  Government  surveyor  in  this  matter 
is,  to  keep  the  image  square  between  the  equatorial  lines 
during  most  of  the  day,  but  at  morning  and  evening,  when 
the  sun  is  near  the  horizon,  to  run  the  image  full  and  flush 
upon  the  lower  line,  and  pay  no  regard  to  the  other. 

When  the  sun  is  near  the  horizon,  the  image  is  less  bright 
and  clearly  defined  than  during  the  rest  of  the  day,  and  in 
keeping  the  brightest  part  fully  on  the  lower  equatorial  line, 
as  we  have  said,  the  hazy  edge  of  the  image  will  overlap 
one  or  two  of  the  graduated  spaces  below,  and  thus  fully 
compensate  for  the  effect  of  refraction. 

A  little  practice  with  the  instrument  will  soon  enable  the 
inexperienced  surveyor  to  supply  the  correction  thus  ap- 
proximately given,  so  as  to  make  the  proper  allowance  for 
incidental  refraction  with  more  accuracy,  than  if  a  precise 
calculation  had  been  attempted. 

Use  of  the  Needle. — In  running  lines,  the  magnetic  needle 
is  alway  kept  with  the  sun  ;  that  is,  the  point  of  the  needle 
is  made  to  indicate  0  on  the  arc  of  the  compass  box,  by 
turning  the  tangent  screw  connected  with  its  arm  on  tlie 
opposite  side  of  the  plate.  By  this  means  the  lines  can  be 
run  by  the  needle  alone  in  case  of  the  temporary  disappear 


THE  SOLAR  COMPASS. 


87 


ance  of  the  sun  ;  but,  of  course,  in  such  cases  the  surveyor 
must  be  sure  that  no  local  attraction  is  exerted. 

The  variation  of  the  needle,  which  is  noted  at  every  station, 
is  read  off  in  degrees  and  minutes  on  the  arc,  by  the  edge  of 
which  the  vernier  of  the  needle  box  moves. 

Allowance  for  the  Earth's  Curvature. — When  long  lines 
are  run  by  the  Solar  Compass,  either  by  the  true  meridian,  or 
due  east  and  west,  allowance  must  be  made  for  the  curvature 
of  the  earth. 

Thus,  in  running  north  or  south,  the  latitude  changes 
about  one  minute  for  every  distance  of  92  chains,  30  links, 
and  the  side  of  a  township  requires  a  change  on  the  latitude 
arc  of  5'  12'',  the  township,  of  course,  being  six  miles  square. 

This  allowance  is  of  constant  use  where  the  surveyor  fails 
to  get  an  observation  on  the  sun  at  noon,  and  is  a  very  close 
approximation  to  the  truth. 

In  running  due  east  and  west,  as  in  tracing  the  standard 
parallels  of  latitude,  the  sights  are  set  at  90o  on  the  limb, 
and  the  line  is  run  at  right  angles  to  the  meridian. 

If  no  allowance  were  made  for  the  earth's  curvature,  these 
lines  would,  if  sufficiently  produced,  reach  the  equator,  to 
which  they  are  constantly  tending. 

Of  course,  in  running  short  lines  either  east  or  west,  the 
variation  from  the  parallel,  would  be  so  small  as  to  be  of  no 
practical  importance,  but  when  long  sights  are  taken,  the 
correction  should  be  made  by  taking  fore  and  back  sights  at 
every  station,  noticing  the  error  on  the  back  sight,  and  set- 
ting off  one  half  of  it  on  the  fore  sight  on  the  side  towards 
the  pole. 

Time  op  Day  by  the  Sun. — The  time  of  day  is  best  ascer- 
tained by  the  Solar  Compass  when  the  sun  is  on  the  meridian, 
as  at  the  time  of  making  the  observation  for  latitude. 

The  time  thus  given  is  that  of  apparent  noon,  and  can  be 
reduced  to  mean  time,  by  merely  applying  the  equation  of 


88 


THE  SOLAR  COMPASS. 


time  as  directed  in  the  Almanac,  and  adding  or  subtracting 
as  the  sun  is  slow  or  fast. 

The  time,  of  course,  can  also  be  taken  before  or  after  noon, 
by  bringing  the  sun's  image  between  the  hour  lines,  and 
aoticing  the  position  of  the  divided  edge  of  the  revolving 
arm,  with  reference  to  the  graduations  of  the  hour  circle, 
allowing  four  minutes  of  time  for  each  degree  of  the  arc,  and 
thus  obtaining  apparent  time,  which  must  be  corrected  by 
the  equation  of  time  as  just  described. 

Caution  as  to  the  False  Image. — In  using  the  compass 
upon  the  sun,  if  the  revolving  arm  be  turned  a  little  one  side 
of  its  proper  position,  a  false  or  reflected  image  of  the  sun 
will  appear  on  the  silver  plate  in  nearly  the  same  place  as 
that  occupied  by  the  true  one.  It  is  caused  by  the  reflection 
of  the  true  image  from  the  surface  of  the  arm,  and  is  a  fruit- 
ful source  of  error  to  the  inexperienced  surveyor.  It  can, 
however,  be  readily  distinguished  from  the  real  image  by 
being  much  less  bright,  and  not  so  clearly  defined. 

Approximate  Bearings. — When  the  bearings  of  lines,  such 
as  the  course  of  a  stream,  or  the  boundaries  of  a  forest, 
are  not  desired  with  the  certainty  given  by  the  verniers  and 
horizontal  limb,  a  rough  approximation  of  the  angle  they 
make  with  the  true  meridian,  is  obtained  by  the  divisions  on 
the  outside  of  the  circular  plate. 

In  this  operation,  a  pencil,  or  thin  straight  edge  of  any 
Bort,  is  held  perpendicularly  against  the  circular  edge  of  the 
plate,  and  moved  around  until  it  is  in  range  with  the  eye, 
the  brass  centre  pin,  and  the  object  observed. 

The  bearing  of  the  line  is  then  read  off  at  the  point  where 
the  pencil  is  placed. 

Time  for  using  the  Solar  Compass. 
The  Solar  Compass,  like  the  ordinary  instrument,  can  be 
used  at  all  seasons  of  the  year,  the  most  favorable  time 


THE  SOLAR  COMPASS. 


89 


being,  of  course,  in  the  summer,  when  the  declination  is 
north,  and  the  days  are  long,  and  more  generally  fair. 

It  is  best  not  to  take  the  sun  at  morning  and  evening, 
when  it  is  within  half-an-hour  of  the  horizon,  nor  at  noon,  aa 
we  have  before  stated,  for  about  the  same  interval,  before 
and  after  it  passes  the  meridian. 

Telescope  and  Micrometer. 

It  is  often  desirable  to  use  a  telescope  in  connection  with 
the  Solar  Compass,  both  for  ranging  lines  and  measuring 
distances,  where  the  chain  cannot  be  conveniently  employed. 


The  above  cut  will  show  the  arrangement  which  we  have 
commonly  made  for  this  purpose,  and  which  is  intended  to 
use  with  that  form  of  the  instrument  provided  with  the 
ordinary  sights. 

The  telescope  is  from  It  to  20  inches  in  length,  and  fur- 
nished with  the  same  glasses  as  those  of  the  best  leveling 
instruments. 

It  has,  of  course,  the  ordinary  cross-wires,  with  screws  for 
their  adjustment  ;  the  centering  ring  for  the  eye-piece,  the 
screws  and  washers  of  which  are  shown  at  the  eye  end;  and 
a  pinion  for  bringing  the  object  glass  into  focus  upon  neai 
and  distant  objects. 

The  tube  of  the  telescopo  is  placed  in  Y  pieces  like  those 
of  the  leveling  instrument,  so  that  it  can  be  revolved  at 


90 


TEE  SOLAR  COMPASS. 


pleasure  on  loosening  the  pins  which  confine  it,  or  entirely 
removed  from  the  wyes,  and  carried  on  the  person  of  the 
surveyor,  by  a  cord  suspended  from  the  little  rings  shown 
on  its  upper  surface. 

The  wye  piece  on  the  forward  sight  has  a  slote  as  shown, 
so  as  to  allow  the  telescope  to  move  up  or  down  a  short 
distance,  and  to  be  clamped  at  pleasure  at  any  point  within 
the  range. 

The  cross-wire  screws  are  concealed  under  a  little  thin 
brass  ferule,  placed  on  the  enlarged  part  of  the  tube,  which 
can  be  slipped  off,  whenever  the  adjustment  of  the  wires  is 
required. 

The  cross-wires  are  adjusted  like  those  of  the  ordinary 
level,  by  revolving  the  tube  in  the  wyes,  and  bringing  each 
wire  to  reverse  upon  the  same  object. 

When  thus  adjusted,  the  telescope  is  turned  in  the  wyes, 
until  the  pinion  is  in  the  position  shown  in  the  cut,  and  the 
wires  made  respectively  horizontal  and  vertical,  when  it  is 
clamped  by  the  pins,  and  the  telescope  moved  up  >r  down 
at  the  forward  end,  and  finally  clamped  upon  the  sights,  so 
that  the  vertical  wire  and  the  compass  sights  bisect  the 
game  object  observed. 

The  telescope  can  then  be  used  in  place  of  the  sights,  and 
long  lines  over  surfaces  nearly  horizontal  be  run  with  nearly 
the  same  accuracy  and  ease  as  with  the  Transit. 

When  packed  in  the  instrument  case,  the  tube  of  the 
telescope  takes  apart  by  unscrewing  in  the  middle,  there 
being  also  little  caps  supplied  to  screw  on  the  open  ends, 
and  keep  out  the  dust  and  moisture  from  the  interior  of  the 
tube. 

The  Cheaper  Telescope. — In  place  of  the  telescope  we 
have  just  described,  a  much  cheaper  one  is  sometimes  made 
by  adapting  the  ordinary  spy-glass  to  the  sights,  and  sup* 
plying  the  cross  wires. 


THE  SOLAR  COMPASS. 


91 


This  telescope,  however,  cannot  be  adjusted  with  certainty, 
or  used  with  satisfaction,  nor  can  it  be  recommended  where 
accuracy  of  observation  is  required. 

Micrometer. — In  this  telescope  there  are  three  horizontal 
cross  wires,  the  centre  one  being  fixed  as  usual,  while  the  otlers, 
one  on  either  side,  can  be  adjusted  at  any  distance  from  each 
other,  and  thus  made  to  cover  a  certain  interval  upon  a  rod 
placed  at  a  specified  distance  from  the  telescope. 

When  these  wires  are  thus  adjusted  to  include  a  certain 
interval,  as  a  foot  for  instance,  upon  a  rod  placed  at  a  distance 
of  100  feet,  it  is  found  that  they  will  cover  half  a  foot  at  one 
half  that  distance,  or  two  feet  at  a  distance  of  200  feet,  and 
go  on  in  very  nearly  the  same  proportion. 

By  this  means  the  distance  of  the  rod  from  the  instrument 
can  be  measured  or  set  ofi",  without  the  use  of  a  chain,  and 
with  astonishing;  accuracy  and  ease. 

Indeed,  we  have  been  frequently  assured  that  with  a  power- 
ful telescope,  such  as  we  have  often  placed  on  our  transit 
instruments,  or  such  as  we  are  now  describing,  distances  can 
be  measured  with  even  greater  accuracy  than  by  a  chain, 
especially  when  the  surface  of  the  ground  is  broken  or  inter- 
sected by  deep  ravines. 

The  two  small  screws  by  which  the  movable  wires  are  ad- 
justed, have  their  heads  upon  the  outside  of  the  washers  of 
the  cross  wire  screws,  and  can  thus  be  moved  by  the  surveyor 
with  a  simple  screw  driver,  one  being  slackened  and  the  other 
tightened,  until  the  interval  between  the  wires  is  made  pre- 
cisely as  desired,  when  the  little  movable  ferule  is  slipped  over 
all,  and  the  wires  protected  from  any  derangement. 

When  measurements  are  to  be  recorded  in  chains  and  links, 
the  wires  should  be  made  to  cover  a  foot  at  a  distance  of  66 
feet,  if  recorded  in  feet,  they  should  cover  the  same  interval 
at  a  distance  of  100  feet. 


92 


THE  SOLAR  COMPASS. 


The  rod  used  with  the  micrometer  should  be  graduated  to 
feet  and  decimals  of  a  foot,  and  provided  with  two  targets, 
the  upper  one  being  fixed  at  some  definite  point,  while  the 
lower  one  can  be  moved  as  the  surveyor  requires,  the  dis- 
tance between  the  two  targets  being  accurately  read  off  by 
the  vernier  of  the  movable  one. 

In  using  the  micrometer,  the  upper  wire  is  brought  by  the 
leveling  screws  of  the  tripod  precisely  upon  the  upper  or 
stationary  target,  while  the  lower  target  is  moved  up  or 
down  until  the  lower  wire  exactly  bisects  its  centre  line, 
when  tbe  rod  is  read,  and  the  distance  recorded. 

Different  Forms  of  the  Solar  Compass, 

We  manufacture  two  different  forms  of  this  instrument,  of 
which  we  will  now  proceed  to  give  a  detailed  description, 
begi^^ning  with  that  of  which  we  have  already  spoken. 


THE  SOLAR  COMPASS. 

Fig.  16. 


The  first  form  of  this  instrument,  and  that  which  is  most  com- 
Tionly  used  by  the  government  surveyor,  is  shown  in  fig,  16, 
and  still  better  in  the  engraving  at  the  opening  of  this  articla 


THE  SOLAK  COMPASS. 


93 


As  there  seen,  the  main  plate  which  carries  the  sights, 
&c.,  is  but  a  trifle  larger  than  the  circular  one  on  which  the 
solar  work  is  placed.  , 

The  solar  apparatus,  which  is  of  the  usual  form  and  size, 
is  permanently  attached  to  the  sockets  of  the  instrument  by 
a  screw,  the  head  of  which  may  be  seen  in  the  inside  of  the 
socket  when  the  instrument  is  removed  from  the  ball. 

The  Sockets  are  very  strong,  and  the  whole  instrument  is 
exceedingly  compact,  light,  and  substantial. 

The  Tangent  Movement  between  the  plates  is  partly  shown 
in  the  figure,  the  clamp  screw,  however,  is  concealed. 

The  Clamp  Screw,  by  which  the  instrument  is  fastened  to 
the  spindle,  is  shown  on  the  side  of  the  socket. 

The  Spring  Catch,  of  which  the  knob  is  shown  opposite 
the  head  of  the  clamp  screw,  prevents  the  instrument  from 
falling  from  the  spindle  when  carried  on  the  shoulder,  with- 
out being  previously  clamped. 

The  lines  of  refraction  are  shown  on  one  of  the  sights,  but 
as  we  have  previously  remarked,  are  very  seldom  used  in 
practice. 

The  Tangent  Scale  for  angles  of  elevation  and  depression 
is  also  seen  upon  the  sights,  and  is  sometimes  of  service  in 
reducing  an  inclined  to  a  horizontal  surface  in  chaining. 

The  Graduations  of  this  instrument  are  made  upon  silver 
plate,  and  figured  as  usual,  the  arcs  and  circles  being  read 
to  single  minutes  by  their  respective  verniers. 

The  Solar  Apparatus  has  the  same  adjustments  and 
appliances  as  have  been  previously  described. 

This  form  of  the  Solar  Compass  is  generally  used  upon  the 
adjusting  socket  shown  in  fig.  14,  but  may  also  be  placed 
upon  the  leveling  tripod  if  desired. 


94 


THE  SOLAK  TELESCOPE  COMPASS. 


THE  SOLAE  TELESCOPE  COMPASS. 

In  this,  the  second  form  of  our  improved  Solar  Compass, 
the  solar  apparatus  and  the  arrangement  of  the  socket,  <fec., 
is  precisely  like  that  of  the  instrument  just  described. 

The  main  or  lower  plate,  however,  is  now  made  circular, 
the  sights  being  dispensed  with,  and  a  telescope  substituted 
in  their  stead. 

The  telescope  is  from  ten  to  twelve  inches  long,  furnished 
with  cross  wires,  &c.,  and  turns  by  its  projecting  spindle 
within  a  socket  attached  to  the  lower  plate  of  the  instru- 
ment, so  as  to  revolve  in  either  direction,  as  in  taking  fore 
and  back  sights,  or  to  run  lines  up  or  down  steep  ascents  or 
descents,  with  the  same  ease  as  that  of  the  ordinary  Transit. 

Attached  to  the  ball  of  the  telescope,  and  turning  with  it, 
is  also  shown  an  index,  with  vernier  reading  to  five  minutes, 
which  moving  over  a  graduated  circle,  enables  the  surveyor 
to  take  angles  of  elevation  and  depression  with  great  facihty. 

The  telescope  is  also  furnished  with  the  micrometer  wires 
already  described,  the  movable  wire  being  adjusted  by  the 
small  screw  heads  shown  above  and  below  to  one  side  of 
those  which  effect  the  ordinary  adjustment  of  the  wires. 

The  socket  in  which  the  spindle  of  the  telescope  turns,  is 
moved  at  one  end  a  short  distance  in  a  horizontal  direction 
by  butting  screws  pressing  upon  either  side,  thus  adjusting 
the  cross  wires  of  the  telescope  precisely  to  the  equatorial 
sights  of  the  solar  apparatus,  as  described  in  our  4th  adjust- 
ment of  the  Solar  Compass. 

This  instrument  is  best  used  upon  the  light  leveling 
tripod,  as  shown  in  the  engraving ;  but  the  adjusting 
socket,  fig.  14,  is  also  supplied  with  each  instrument,  and 
being  fitted  to  the  same  tripod,  can  be  substituted  whenever 
desired. 


Made  bv 


Made  by 


/  / 


THE  SOLAR  TELESCOPE  COMPASS. 


95 


To  use  the  Solar  Telescope  Compass. 


As  the  construction  of  this  form  of  the  Solar  Compass  is 
somewhat  peculiar,  on  account  of  the  telescope  and  its 
position  on  the  instrument,  a  brief  explanation  of  its  use 
may  here  be  appropriately  made. 

The  fact  that  in  this  instrument  the  telescope  is  placed  at 
one  side,  may  at  first  occasion  some  question  as  to  the 
accuracy  and  convenience  of  its  observation. 

A  very  simple  contrivance  adapted  to  the  flagstaff  used 
with  the  instrument,  will,  however,  we  think,  obviate  any 
difficulty  in  both  respects. 

This  is  shown  in  fig.  18,  and  is  merely  a  small  peg  or 
offset  fastened  near  the  foot  of  the  staff,  its  extremity  being 
precisely  the  same  distance  from  the  centre  of  the  staff  as 
the  centre  of  the  telescope  is  from  that  of  the  instrument 


The  staff  is  therefore  held  so  that  the  offset  is  at  right 
angles  to  the  direction  of  the  line  run,  and  being  put  in 
position  by  the  telescope,  the  pin  or  stake  is  set  at  the 
extremity  of  the  offset,  and  is  therefore  i;^  the  true  line. 


When  the  instrument  is  brought  up  to  the  point  thus 
found,  its  centre  is  set  over  the  stake,  and  another  observa- 


itself. 


Fig.  18. 


A. 


C 


96 


THE  SOLAR  TELESCOPE  COMPASS. 


tion  made  in  precisely  tlie  same  manner,  the  staff  and  the 
centre  of  the  telescope  being  thus  always  to  one  side  of  the 
true  line,  while  the  centre  of  the  instrument,  and  the  ex- 
tremity of  the  offset  pin,  are  directly  upon  it. 

Thus,  in  fig.  18,  E  F  represents  a  portion  of  the  staff, 
showing  the  offset  pin  at  its  base,  and  the  accompanying 
diagram  illustrates  the  manner  of  running  lines. 

Suppose  the  instrument  set  at  A,  and  it  is  required  to 
run  the  line  A  B ;  the  telescope  represented  at  the  side  of 
the  circle  will  locate  the  position  of  the  staff  at  the  end  of 
the  line,  just  as  far  to  one  side,  as  it  is  itself  to  one  side  of 
the  centre  of  the  instrument. 

But  the  end  of  the  offset  pin  is  now  precisely  in  the  true 
line,  as  shown  at  the  point  B,  and  the  result  is  precisely  the 
same  as  if  the  telescope  was  placed  over  the  centre  of  the 
instrument,  and  the  rod  without  an  offset. 

If  it  is  required  to  set  off  another  line  C  D  at  a  given 
point  C,  at  any  given  angle  with  the  line  A  B,  the  instru- 
ment is  set  over  C,  the  rod  held  with  the  end  of  the  offset 
towards  the  line,  and  the  observation  made  in  the  same 
manner  as  before. 

To  Adjust  the  Telescope. — The  line  of  collimation  is 
most  conveniently  adjusted  hy  the  second  method  given 
in  our  account  of  the  Vernier  Transit,  and  which  we 
will  here  repeat.  The  instrument  is  set  up  in  a  position 
commanding  a  long  sight  in  the  same  direction,  and  care- 
fully leveled. 

The  plates  and  socket  are  then  securely  clamped,  and 
with  the  telescope  and  offset  staff  above  described,  three 
points,  which  we  will  term  ABC,  are  located  in  the  same 
direction  at  distances  from  the  instrument  at  about  one, 
two,  and  three  hundred  feet  respectively. 

These  points,  which  may  be  marked  by  setting  a  marking 
pin,  or  driving  in  a  stake,  will  all  be  in  the  same  straight 


THE  SOLAR  TELESCOPE  COMPASS. 


97 


line,  however  mucli  tlie  wires  are  out  of  adjustment,  since 
the  position  of  the  telescope  remains  unchanged  during  the 
whole  operation. 

The  instrument  is  now  moved  to  B,  its  centre  set  carefully 
over  it  by  a  plumb  ball,  again  leveled  and  clamped,  and  the 
telescope  directed  to  the  offset  staff  set  at  A  or  C,  and  re- 
volved in  the  opposite  direction. 

If  the  vertical  wire  strikes  the  opposite  point,  the  telescope 
is  in  adjustment  J  if  not,  with  the  screws  bring  the  wire  half 
way  over  the  error,  and  again  observe  the  same  points  as 
before,  when,  if  the  proper  correction  has  been  made,  the 
wire  will  bisect  the  staff  at  both,  and  the  telescope  will  be 
in  adjustment. 

The  screws  which  centre  the  eye-piece  are  shown  nearest 
the  eye  end  of  the  tube,  and  are  used  precisely  like  those  of 
the  Transit. 

The  telescope  is  readily  adjusted  to  the  solar  apparatus 
as  before  described,  by  bringing  it  to  the  same  side  of  the 
instrument  as  that  on  which  the  equatorial  sights  are  placed 
in  the  4th  adjustment,  and  then  the  plates  being  previously 
clamped  at  90°,  and  the  arm  at  0°  on  the  declination  arc ; 
directing  the  sights  to  some  well  marked  and  distant  object, 
which  the  vertical  wire  of  the  telescope  must  also  be 
made  to  bisect,  by  the  two  butting  screws,  which  press  on 
opposite  sides  of  the  socket. 

When  the  adjustment  is  completed,  the  screws  should  be 
brought  firmly  against  the  socket  to  make  it  permanent. 

Superiority  of  our  Solar  Compasses. 
The  Solar  Compass  as  hitherto  made,  though  planned 
with  great  ingenuity  in  its  general  arrangement,  was  still 
extremely  rude  in  its  mechanical  details  and  adjustments. 
Some  of  these  defects,  which  are  apparent  on  inspection  of 
any  instrument,  as  hitherto  made  by  other  manufacturers, 
7 


98 


THE  SOLAR  TELESCOPE  COMPASS. 


and  whicli  must  have  frequently  occurred  to  the  surveyor, 
we  will  now  enumerate. 

The  motion  of  the  plates  over  each  other  was  accompanied 
with  so  much  friction,  that  in  turning  the  verniers  around 
the  limb,  the  whole  instrument  would  often  be  moved  about 
its  spindle. 

Again,  the  verniers  must  be  set,  and  the  sights  directed  to 
an  object  by  the  hand  alone,  a  matter  of  no  little  difficulty 
when  single  minutes  of  a  degree  were  to  be  set  ofi',  and 
accurate  observations  were  required. 

The  latitude  and  dechnation  arcs  must  also  be  moved  by 
hand,  and  the  verniers  set  to  single  minutes  in  the  same 
manner. 

The  points  in  which  we  claim  the  superiority  of  our  Solar 
Compass  over  any  hitherto  manufactured,  and  by  means  of 
which  the  defects  just  enumerated  are  entirely  removed, 
a:re  partially  shown  in  the  various  cuts  already  given,  and 
will  now  be  stated  in  detail. 

1.  A  motion  of  the  horizontal  plates  almost  entirely  free 
from  friction,  combined  with  perfect  sohdity. 

2.  A  fine  clamp  and  tangent  movement  to  the  divided 
limb,  as  shown  in  the  figures  under  the  plate. 

3.  A  tangent  movement  with  clamp,  for  the  declination 
arc,  as  shown  at  k. 

4.  A  tangent  movement  with  clamp  to  the  latitude  arc,  as 
shown  at /. 

5.  A  tangent  motion  for  the  whole  instrument  about  its 
sockets,  as  shown  in  our  Adjusting  Socket. 

6.  The  employment  of  a  telescope  in  place  of  sights,  as  in 
our  second  form  of  the  instrument. 

7.  G-reat  facility  of  adjustment,  and,  in  consequence,  an 
important  saving  of  time. 

8.  An  important  reduction  in  price,  while  still  furnishing 
an  article  greatly  improved. 


THE  SOLAR  COMPASS. 


99 


Weight  of  the  Solar  Compass, 
The  average  weights  of  the  different  forms  of  this  instru- 
ment which  we  manufacture  are  as  follows  : 

Solar  Compass  proper,  with  adjusting  socket ....  12  lbs. 
Solar  Telescope  Compass,       "  "   12  lbs. 

Advantages  of  the  Solar  Compass  in  Surveying. 

It  will  readily  occur  to  all  who  have  read  the  preceding 
description  of  the  Solar  Compass,  that  while  it  is  indis- 
pensable in  the  surveys  of  public  lands,  it  also  possesses 
important  advantages  over  the  magnetic  compass,  when 
used  in  the  ordinary  surveys  of  farms,  &c. 

For  not  only  can  lines  be  run  and  angles  be  measured 
without  regard  to  the  diurnal  variation,  or  the  effect  of  local 
attraction,  but  the  bearings  being  taken  from  the  true 
meridian,  will  remain  unchanged  for  all  time. 

The  constant  uncertainty  caused  by  the  variation  of  the 
needle,  and  the  litigation  to  which  it  so  often  gives  rise, 
may  thus  be  entirely  prevented  by  the  use  of  the  Solar  Com- 
pass in  this  kind  of  work. 

It  is  also  said  by  those  familiar  with  the  use  of  this 
instrument,  that,  in  favorable  weather,  surveys  can  be  more 
rapidly  made  with  it  than  with  the  ordinary  needle  in- 
strument; there  being  no  time  consumed  in  waiting  for 
the  needle  to  settle,  or  in  avoiding  the  errors  of  local 
attraction. 

When  the  sun  is  obscured,  the  lines  may  be  run  by  the 
needle  alone,  it  being  always  kept  with  the  sun,  or  at  0 
on  its  arc,  and  thus  indicating  the  direction  of  the  true 
meridian. 

The  sun,  however,  must  ever  be  regarded  as  the  most 
rehable  guide,  and  should,  if  possible,  be  taken  at  every 
station. 


100 


THE  SOLAR  COMPASS. 


It  is  with  the  design  of  making  the  principles  and  use  of 
the  Solar  Compass  intelligible  to  the  ordinary  surveyor,  that 
we  have  given  a  more  extended  account  of  this  instrument 
than  of  the  others  previously  mentioned,  believing  that 
when  its  merits  become  better  understood,  it  will  come  into 
more  general  use. 

For  much  valuable  information  as  to  the  details  of  this 
instrument,  as  well  as  the  practice  of  government  sur- 
veyors in  the  field,  we  are  indebted  to  our  friend  James 
L.  Inoallsbe,  late  U.  S.  Deputy  Surveyor  in  Iowa,  Kansas 
and  Nebraska. 


Made  by 


BEN.J  r>.  BENSON.  J>T.T 


THE  engineer's  TRANSIT. 


101 


Engineers*  Instrnments. 


THE  ENGINEEE'S  TKANSIT. 

Having  now  described  the  various  instruments  employed 
in  surveying,  we  shall  consider  those  whose  use  belongs  more 
especially  to  the  practice  of  the  civil  engineer,  and  of  these 
the  first  in  importance  is  that  termed  the  Engineer's  Transit. 

The  engraving  will  convey  a  good  idea  of  our  latest  im- 
proved Engineer's  Transit,  and  to  this  the  reader  will  please 
refer  in  the  following  detailed  description  of  its  different  parts. 

The  Telescope  is  from  eleven  to  twelve  inches  long,  and 
is  of  the  finest  quality. 

Like  those  of  our  other  instruments,  it  is  capable  of  rever- 
sion always  at  the  eye  end,  and  we  now  most  commonly 
make  both  ends  to  reverse. 

The  rack  and  pinion  movement  of  the  object-glass  is 
usually  placed,  as  shown,  on  the  side  of  the  telescope  tube, 
though  sometimes  on  the  top,  as  the  engineer  may  prefer. 

Pinion  to  the  Eye-Glass. — We  have  often  adapted  to  the 
eye-piece  of  this  and  our  other  Transits  a  rack  and  pinion 
movement,  which  is  placed  on  the  side  of  the  tube,  and  is 
very  excellent  in  bringing  the  cross-wires  precisely  into  focus. 

A  spiral  adjustment  of  the  eye-piece  is  also  used  by  us 
in  the  telescopes  of  all  our  transits,  by  which,  when  the 
milled  head  of  the  eye-piece  is  twisted  in  either  direction, 
as  may  be  needed,  the  eye-piece  is  brought  into  focus  with 
ease  and  accuracy. 

The  Shade. — A  short  piece  of  thin  tube  called  the  shade, 
is  always  made  to  accompany  this  and  the  previous  instru- 
ments, and  is  used  to  protect  the  object-o'lRss  from  the  s'lare 


102 


THE  engineer's  TRANSIT. 


of  the  sun,  or  from  moisture  ;  it  must  be  removed  whenever 
the  telescope  is  reversed,  unless  the  telescope  is  made  to 
reverse  at  the  eye-end,  as  is  generally  desired. 

The  interior  construction  of  the  telescope  is  similar  to 
those  already  described. 

The  Standards  are  made  of  well-hammered  brass,  firm  and 
strong. 

On  one  of  them  will  be  seen  the  little  movable  box  with  the 
capstan  head  screw  underneath,  by  which  the  cross-wires 
are  adjusted  to  trace  a  vertical  line,  as  described  on  page 
42  in  our  account  of  the  Vernier  Transit. 

The  Limb  or  divided  circle  is  seven  inches  in  diameter, 
graduated  to  half  degrees,  and  read  by  two  opposite  verniers 
to  single  minutes. 

The  Verniers  are  double,  reading  both  ways  from  the 
centre,  and  are  placed  on  the  sides  of  the  plate  at  right 
angles  to  the  telescope. 

The  Needle  is  five  inches  long,  and  is  raised  by  a  milled 
screw  head  shown  in  the  cut,  placed  above  the  plate. 

The  Clamp  and  Tangent  Screws  are  also  above,  so  as  to  be 
very  accessible,  and  out  of  the  reach  of  ordinary  accidents. 
The  clamping  of  the  limb  is  effected  in  the  interior,  the 
aperture  being  covered  with  a  washer  to  exclude  the  dust 
and  moisture. 

The  Levels,  as  shown  in  the  cut,  are  above  ;  they  are 
both  adjustable  with  the  ordinary  steel  pin. 

The  glass  vials  used  in  the  levels  of  this  and  the  Sur- 
veyor's Transit,  are  ground  on  their  upper  interior  surface, 
BO  that  the  bubble  moves  very  evenly  and  with  great  seni^i 
tiveness. 

The  Tripod  Head  of  this  instrument  is  made  considerat 
heavier  than  that  of  the  Surveyor's  Transit. 

The  upper  plate  is  about  five  inches  diameter,  made  thick 
and  of  well  hammered  brass  j  into  this  are  screwed  the  long 


THE  engineer's  TRANSIT. 


103 


nuts  or  sockets  for  the  leveling  screws,  and  on  the  upper 
surface  is  seeu  the  clamp,  with  the  two  butting  tangent 
screws. 

With  these  the  movement  is  made  very  slowly,  and  much 
more  firmly  than  is  possible  with  a  single  tangent  screw. 

The  leveling  screws  are  of  bell  metal,  and  have  a  broad 
three  milled  head  ;  they  rest  on  the  lower  plate,  in  the  little 
cups  spoken  of  in  our  account  of  the  previous  instrument. 

In  the  engraving  it  will  also  be  seen  that  the  screws  are 
entirely  covered  above  the  plate,  by  little  brass  caps  which 
protect  the  threads  from  dust  and  corrosion. 

The  lower  plate  is  a  little  smaller  than  the  upper,  milled 
on  the  edge,  and  made  to  connect  by  a  screw,  with  the  tripod 
legs. 

This  tripod  head  is  attached  to  the  sockets  of  the  limb 
and  vernier  plate,  and  is  removed  with  them,  when  the  in- 
Btrument  is  packed  in  the  box  for  transportation. 

The  loop  for  the  plumb-bob  is  connected  by  a  screw  to  the 
spindle  of  the  vernier  plate,  so  that  it  is  always  suspended 
from  the  exact  centre  of  the  instrument. 

The  Attachments  of  the  Transit. 

The  engraving  of  the  Surveyor's  Transit  shows  the  verti- 
cal circle  of  four  and  a  half  inches  diameter,  which  is  read 
by  a  double  vernier  to  minutes,  and  also  the  clamp  and 
tangent  movement  to  the  axis  of  the  telescope. 

These,  with  the  addition  of  a  level  on  the  telescope,  are 
ofti.n  used  with  this  instrument,  though  the  majority  of 
engineers  prefer  an  instrument  with  plain  telescope,"  like 
that  shown  in  the  engraving. 

Micrometer, 

Jt  ifi  sometimes  very  convenient  in  the  use  of  both  the 
Transit  and  Leveling  Instrument,  to  employ  some  simple 


104 


THE  engineer's  TRANSIT. 


method  of  ascertaining  the  distances  of  objects  without  re« 
sorting  to  actual  measurements. 

This  is  well  effected  by  what  is  termed  a  "Micrometer,"  bj 
the  French  called  ^'  Stadia,''  the  construction  and  use  of 
which  we  have  already  given  on  pages  89  —  91,  in  our 
account  of  the  Solar  Compass. 

The  two  small  screws  which  adjust  the  movable  wire,  are 
placed  on  opposite  sides  of  the  telescope,  and  to  one  side  of 
the  ordinary  cross-wire  screws,  precisely  as  shown  in  fig.  17, 
and  the  wire  is  moved  by  alternately  loosening  one  and 
tightening  the  other,  until  the  two  horizontal  wires  are  made 
to  cover  the  interval  desired. 

The  micrometer  wire  is  furnished,  whenever  desired,  with 
any  of  our  transits,  and  without  additional  charge. 

To  adjmt  the  Transit 
The  adjustments  of  this  instrument  and  its  attachments 
have  been  described  in  our  account  of  those  previously 
considered. 

To  use  the  Engineer's  Transit. 

But  little  need  be  added  to  what  has  been  already  given 
in  the  previous  pages. 

The  Needle  is  of  service  principally  as  a  rough  check 
upon  the  readings  of  the  verniers  in  the  measurement  of 
horizontal  angles,  any  glaring  mistake  being  detected,  by 
noticing  the  angles  indicated  by  both,  in  the  different  posi- 
tions of  the  telescope. 

It  may  also  be  used  as  in  the  compass,  to  give  the  direc- 
tion in  which  the  lines  are  run,  but  its  employment  is  only 
subsidiary  to  the  general  purposes  of  the  Transit. 

Size  of  the  Engineer's  Transit, 
We  make  two  different  sizes  of  this  instrument,  viz : 
The  Five-Inch  Transit  just  described,  which,  exclusive  of 
the  tripod  legs,  weighs  about  I3|  lbs.,  and  the 


THE  ENGINEER'S  TRANSIT. 


105 


Four-Inch  Transit,  precisely  similar  in  style,  but  about 
one-fourth  smaller  and  lighter  in  all  its  parts. 

It  has  a  telescope  of  about  ten  inches  long,  a  four-inch 
needle,  and  a  divided  limb  of  six  inches  diameter. 

Weight  of  the  Attachments. 

As^it  may  sometimes  be  desirable  to  know  the  weights  of 
the  different  extras  or  attachments,  often  used  in  this  and  the 
other  Transits  previously  described,  we  here  add  them  in 
detail. 

Ground  level  tube,  with  vial  complete. .  7 J  oz. 

Vertical  circle,  with  vernier  6  oz. 

Clamp  and  tangent  to  axis  4  oz. 

Besides  the  simple  form  of  the  Engineer's  Transit,  we  also 
make  important  modifications,  which  may  be  desired  by  the 
engineer  ;  a  few  of  these  we  shall  now  enumerate. 

The  Watch  Telescope, 

A  telescope  is  sometimes  attached  to  a  socket,  moving  in 
a  hollow  cylinder  which  surrounds  the  lengthened  socket  of 
tfte  limb,  and  is  thus  capable  of  moving  around  under  the 
plates,  and  of  a  short  vertical  motion. 

The  cylinder  which  supports  it,  may  be  clamped  firmly  to 
the  limb,  and  the  wires  of  the  telescope  thus  fixed  upon  any 
object,  by  the  tangent  movement  of  the  tripod  head. 

The  object  of  the  watch  telescope,  is  to  guard  against,  and 
detect  any  inaccuracy  arising  from  the  disturbance  of  the 
limb,  during  the  progress  of  an  observation,  or  the  measure- 
ment of  angles. 

Thus,  if  the  wires  of  both  telescopes  are  fixed  upon  the  ^ 
same  object,  and  the  watch  telescope  kept  still  upon  it,  while 
the  vernier  plate  is  undamped,  and  the  upper  telescope 
shifted  to  the  second  point,  a  reference  to  the  watch  tele- 
scope will  immediately  betray  any  disturbance  in  the  posi 
tion  of  the  limb. 


106 


THE  engineer's  TRANSIT. 


But,  in  spite  of  its  excellencies  in  cases  where  great  nicety 
is  required,  the  additional  weight  and  complication  of  the 
watch  telescope,  have  caused  it  to  be  regarded  by  most 
American  engineers  as  an  incumbrance,  rather  than  an  ad- 
vantage to  the  Transit. 

The  Theodolite  Axis, 

In  place  of  the  ordinary  axis  of  the  telescope  represented 
in  our  engraving,  we  sometimes  make  one  resembling  the  Y 
axis  of  the  English  Theodolite. 

This  modification  is  desirable,  in  cases  where  this  instru- 
ment is  intended  to  subserve  the  purposes  of  both  level  and 
transit. 

In  such  an  arrangement,  the  telescope  is  confined  in  the 
axis  with  clips,  by  loosening  which,  it  may  be  revolved  in 
the  wyes,  or  taken  out  and  reversed  end  for  end,  precisely 
like  that  of  the  leveling  instrument. 

The  standards  also  allow  its  transit,  or  complete  revolu- 
tion in  a  vertical  direction. 

In  such  an  instrument,  the  adjustment  of  the  wires,  and 
level  of  the  telescope,  is  effected  in  the  same  manner  as 
those  of  the  leveling  instrument,  the  tangent  movement 
of  the  axis  serving,  instead  of  the  leveling  screws,  to  bring 
the  bubble  and  wires  into  position. 

With  this  modification  of  the  Transit,  we  have  also  fre- 
quently added,  that  of  a  small  level  bar,  wyes,  &c.,  into 
which  the  telescope  may  be  transferred,  making  thus  a 
miniature  leveling  instrument. 

This  may  be  placed  upon  the  socket  and  tripod  head  of 
the  transit,  and  thus  made  capable  of  taking  levels  with  a 
good  degree  of  accuracy. 

When  desirable,  a  vertical  wheel  may  be  placed  on  the 
axis  of  the  telescope  of  this  instrument,  and  thus  all  the 
properties  of  the  English  Theodolite  united  with  those  of 
the  American  Transit 


THE  LEVELING  INSTRUMENT. 


107 


THE  LEVELING  INSTRUMENT. 

Of  the  different  varieties  of  the  leveling  instrument,  thai 
termed  the  Y  Level,  has  been  almost  universally  preferre(i 
by  American  engineers,  on  account  of  the  facility  of  its 
adjustment  and  superior  accuracy. 

Of  these  levels  we  manufacture  four  different  sizes,  having 
telescopes  of  sixteen,  eighteen,  twenty,  and  twenty-two 
inches  long,  respectively. 

The  engraving  on  the  opposite  page  represents  our  twenty 
inch  Level,  that  of  the  sixteen  inch  telescope  will  be  shown 
beyond. 

We  shall  consider  the  several  parts  of  the  instrument  in 
detail : 

The  Telescope  has  at  each  end  a  ring  of  bell-metal,  turned 
very  truly  and  both  of  exactly  the  same  diameter  ;  by  these 
it  revolves  in  the  wyes,  or  can  be  at  pleasure  clamped  in  any 
position  when  the  clips  of  the  wyes  are  brought  down  upon 
the  rings,  by  pushing  in  the  tapering  pins. 

The  telescope  has  a  rack  and  pinion  movement  to  both 
object  and  eye-glasses,  an  adjustment  for  centering  the  eye- 
piece, shown  at  A  A,  in  the  longitudinal  section  of  the  tele- 
scope, (page  105,)  and  another  seen  at  C,  C,  for  ensuring  the 
accurate  projection  of  the  object-glass,  in  a  straight  line. 

Both  of  these  are  completely  concealed  from  observation 
and  disturbance  by  a  thing  ring  which  slides  over  them. 

The  telescope  has  also  a  shade  over  the  object-glass,  so 
made,  that  whilst  it  may  be  readily  moved  on  its  slide  over 
the  glass,  it  cannot  be  dropped  off  and  lost. 

The  shade  of  our  sixteen  inch  level,  is  made  to  take  off, 
like  that  of  the  Engineer's  Transit. 

The  interior  construction  of  the  telescope  will  be  readily 
understood  from  fig.  21,  which  represents  a  longitudinal  sec- 
tion, and  exhibits  the  adjustment  which  ensures  the  accurate 
projection  of  the  object-glass  slide. 


THE  LEVELING  INSTRUMENT. 


As  this  is  peculiar  to  our  instruments, 
and  is  always  made  by  the  maker  so  per- 
manently as  to  need  no  further  attention 
at  the  hands  of  the  engineer,  we  shall  here 
describe  the  means  by  which  it  is  effected, 
somewhat  in  detail. 

The  necessity  for  such  an  adjustment  will 
appear,  when  we  state,  that  it  is  almost 
impossible  to  make  a  telescope  tube,  so 
that  it  shall  be  perfectly  straight  on  its 
interior  surface. 

Such  being*  the  case,  it  is  evident  that 
the  object-glass  slide  which  is  fitted  to 
this  surface,  and  moves  in  it,  must  partake 
of  its  irregularity,  so  that  the  glass  and 
C  the  line  of  collimation  depending  upon  it, 
though  adjusted  in  one  position  of  the  slide 
will  be  thrown  out  when  the  slide  is 
moved  to  a  different  point. 

To  prove  this,  let  any  level  be  selected 
which  is  constructed  in  the  usual  manner, 
^  and  the  line  of  collimation  adjusted  upon 
an  object  taken  as  near  as  the  range  of 
the  slide  will  allow;  then  let  another  be 
selected,  as  distant  as  may  be  clearly  seen; 
upon  this  revolve  the  wires,  and  they  will 
A-  almost  invariably  be  found  out  of  adjust- 
ment, sometimes  to  an  amount  fatal  to  any 
confidence  in  the  accuracy  of  the  instru- 
ment. The  arrangement  adopted  by  us  to 
correct  this  imperfection,  and  which  so 
perfectly  accomplishes  its  purpose,  is 
shown  in  the  adjoining  cut,  fig.  21. 

Here  are  seen  the  two  bearings  of  the 


THE  LEVELING  INSTRUMENT. 


109 


object-glass  slide,  one  being  in  the  narrow  bell-metal  ring, 
which  slightly  contracts  the  diameter  o^  the  main  tube,  the 
other  in  the  small  adjustable  ring,  also  of  bell-metal,  shown 
at  C  C,  and  suspended  by  four  screws  in  the  middle  of  the 
telescope. 

Advantage  is  here  taken  of  the  fact,  that  the  rays  of 
light  are  converged  by  the  object-glass,  so  that  none  are 
obstructed  by  the  contraction  of  the  slide,  except  those 
which  diverge,  and  which  ought  always  to  be  intercepted,  and 
absorbed  in  the  blackened  surface  of  the  interior  of  the  slide. 

Now,  in  such  a  telescope,  the  perfection  of  movement  of 
the  slide,  depends  entirely  upon  its  exterior  surfaces,  at  the 
points  of  the  two  bearings. 

These  surfaces  are  easily  and  accurately  turned,  concentric, 
and  parallel  with  each  other,  and  being  fitted  to  the  rings,  it 
only  remains  necessary  to  adjust  tlie  position  of  the  smaller 
ring,  so  that  its  centre  will  coincide  with  that  of  the  optical 
axis  of  the  object-glass. 

When  this  has  been  once  well  done,  no  further  correction 
will  be  necessary,  unless  the  telescope  should  be  seriously 
injured. 

The  manner  in  which  the  adjustment  of  the  object-glass 
slide  is  effected,  will  be  considered  when  we  come  to  speak 
of  the  other  adjustments. 

Rack  and  Pinion. — As  seen  in  the  engraving,  our  Level 
telescopes  are  usually  furnished  with  the  ordinary  rack  and 
pinion  movement  to  both  object  and  eye  tubes. 

The  advantages  of  an  eye-piece  pinion,  are,  that  the  eye- 
piece can  be  shifted  without  danger  of  disturbing  the  tele- 
Bcope,  and  that  the  wires  are  more  certainly  brought  into 
distinct  view,  so  as  to  avoid  effectually  any  error  of  observa- 
tion, arising  from  what  is  termed  the  instrumental  parallax. 

The  position  of  the  pinion  on  the  tube  is  varied  in  dif« 
ferent  instruments  according  to  the  choice  of  the  engineer. 


110 


THE  LEVELINa  INSTRUMENT, 


We  usually  place  our  object  slide  pinion  on  the  side- 
both  of  Transit  telescopes,  and  of  those  of  the  Level.  The 
pinion  of  the  eye  tube  is  always  placed  on  the  side  of  the  tele* 
scope. 

The  Level  or  ground  bubble  tube  is  attached  to  the  under 
side  of  the  telescope,  and  furnished  at  the  different  ends 
with  the  usual  movements,  in  both  horizontal  and  veitical 
directions. 

The  aperture  of  the  tube,  through  which  the  glass  vial 
appears,  is  about  five  and  one-fourth  inches  long,  being 
crossed  at  the  centre  by  a  small  rib  or  bridge,  which  greatly 
strengthens  the  tube. 

The  level  scale  which  extends  over  the  whole  length,  is 
graduated  into  spaces  a  little  coarser  than  tenths  of  an  inch, 
and  figured  at  every  fifth  division,  counting  from  zero  at  the 
centre  of  the  bridge  ;  the  scale  is  set  close  to  the  glass. 

The  bubble  vial  is  made  of  thick  glass  tube,  selected  so 
as  to  have  an  even  bore  from  end  to  end,  and  finely  ground 
on  its  upper  interior  surface,  that  the  run  of  the  air  bubble 
may  be  uniform  throughout  its  whole  range. 

The  sensitiveness  of  a  ground  level,  is  determined  best  by 
an  instrument  called  a  level  tester,  having  at  one  end  two 
Y^s  to  hold  the  tube,  and  at  the  other  a  micrometer  wheel 
divided  into  hundredths,  and  attached  to  the  top  of  a  fine 
threaded  screw  which  raises  the  end  of  the  tester  very 
gradually. 

The  number  of  divisions  passed  over  on  the  perimeter  of 
the  wheel,  in  carrying  the  bubble  over  a  tenth  of  the  scale, 
is  the  index  of  the  delicacy  of  the  level.  In  the  tester  which 
we  use,  a  movement  of  the  wheel  ten  divisions  to  one  of  the 
scale,  indicates  the  degree  of  delicacy  generally  preferred 
for  railroad  engineering. 

For  canal  work  practice,  a  more  sensitive  bubble  is  often 


THE  LEVELING  INSTRUMENT. 


Ill 


desired,  as  for  instance,  one  of  seven  or  eight  divisions  of 
the  wheel,  to  one  of  the  scale. 

The  Wyes  of  our  levels  are  made  large  and  strong,  of 
the  best  bell-metal,  and  each  have  two  nuts,  both  being 
adjustable  with  the  ordinary  steel  pin. 

The  clips  are  brought  down  on  the  rings  of  the  telescope 
tube  by  the  Y  pins,  which  are  made  tapering,  so  as  to  clamp 
the  rings  very  firmly. 

The  Level  Bar  is  made  round,  of  well  hammered  brass, 
and  shaped,  so  as  to  possess  the  greatest  strength  in  the 
parts  most  subject  to  sudden  strains. 

Connected  with  the  level  bar  is  the  head  of  the  tripod  socket. 

The  Tripod  Socket  is  compound;  the  interior  spindle,  upon 
which  the  whole  instrument  is  supported,  is  made  of  steel, 
and  nicely  ground,  so  as  to  turn  evenly  and  firmly  in  a  hol- 
low c^^linder  of  bell-metal  ;  this  again,  has  its  exterior  sur- 
face fitted  and  ground  to  the  main  socket  of  the  tripod  head. 

The  bronze  cylinder  is  held  upon  the  spindle  by  a  washer 
and  screw,  the  head  of  this  having  a  hole  in  its  centre, 
through  which  the  string  of  the  plumb  bob  is  passed.. 

The  upper  part  of  the  instrument,  with  the  socket,  may 
thus  be  detached  from  the  tripod  head  ;  and  this,  also,  as  in 
the  case  of  all  our  instruments,  can  be  unscrewed  from  the 
legs,  so  that  both  may  be  conveniently  packed  in  the  box. 

A  little  under  the  upper  parallel  plate  of  the  tripod  head, 
and  in  the  main  socket,  is  a  screw  which  can  be  moved  into 
a  corresponding  crease,  turned  on  the  outside  of  the  hollow 
cylinder,  and  thus  made  to  hold  the  instrument  in  the  tripod, 
when  it  is  carried  upon  the  shoulders. 

It  will  be  seen  from  the  engraving,  that  the  arrangement 
just  described  allows  long  sockets,  and  yet  brings  the  whole 
instrument  down  as  closely  as  possible  to  the  tripod  head, 
both  objects  of  great  importance  in  the  construction  of  any 
instrument. 


112 


THE  LEVELING  INSTRUMENT. 


The  Tripod  Head  has  tlie  same  plates  and  leveling  screws 
as  that  described  in  the  account  of  the  Engineer's  Transit ; 
the  tangent  screw,  however,  is  commonly  single. 

For  our  sixteen  inch  level  we  make  a  similar  tripod  head, 
resembling  that  used  with  the  lighter  Engineer's  Transit. 

The  Adjustments. 

Having  now  completed  the  description  of  the  different 
parts  of  the  Leveling  Instrument,  we  are  ready  to  proceed 
with  their  adjustments,  and  shall  begin  with  that  of  the 
object-sHde,  which,  although  always  made  by  the  maker,  so 
permanently  as  to  need  no  further  attention  at  the  hands  of 
the  engineer,  unless  in  cases  of  derangement  by  accident,  is 
yet  peculiar  to  our  instruments,  and  therefore  not  familiar 
to  many  engineers. 

To  Adjust  the  Object  Slide. — The  maker  selects  an 
object  as  distant  as  may  be  distinctly  observed,  and  upon 
it  adjusts  the  line  of  coUimation,  in  the  manner  here- 
after described,  making  the  centre  of  the  wires  to  revolve 
without  passing  either  above  or  below  the  point  or  line 
assumed. 

In  this  position,  the  slide  will  be  drawn  in  nearly  as  far 
as  the  telescope  tube  will  allow. 

He  then,  with  the  pinion  head,  moves  out  the  slide  until 
an  object,  distant  about  ten  or  fifteen  feet,  is  brought  clearly 
into  view  ;  again  revolving  the  telescope  in  the  Y's,  he 
observes  whether  the  wires  wiU  reverse  upon  this  second 
object. 

Should  this  happen  to  be  the  case,  he  will  assume,  that 
as  the  line  of  coUimation  is  in  adjustment  for  these  two 
distances,  it  will  be  so  for  all  intermediate  ones,  since  the 
bearings  of  the  slide  are  supposed  to  be  true,  and  their 
planes  parallel  with  each  other. 

If,  however,  as  is  most  probable,  either  or  both  wires  fail 


THE  LEVELING  INSTRUMENT. 


113 


to  reverse  upon  the  second  point,  he  must  then,  by  estima- 
tion, remove  half  the  error  by  the  screws  C  C,  (fig.  21,)  at 
right  angles  to  the  hair  sought  to  be  corrected,  remember- 
ing, at  the  same  time,  that  on  account  of  the  inversion  of 
•  the  eye-piece,  ho  must  move  the  slide  in  the  direction 
"which  apparently  increases  the  error.  When  both  wires 
have  thus  been  treated  in  succession,  the  line  of  coUimation 
is  adjusted  on  the  near  object,  and  the  telescope  again 
brought  upon  the  most  distant  point ;  here  the  tube  is 
again  revolved,  the  reversion  of  the  wires  upon  the  object 
once  more  tested,  and  the  correction,  if  necessary,  made  in 
precisely  the  same  manner. 

He  proceeds  thus,  until  the  wires  will  reverse  upon  both 
objects  in  succession ;  the  line  of  collimation  will  then  be 
in  adjustment  at  these  and  all  intermediate  points,  and  by 
bringing  the  screw  heads,  in  the  course  of  the  operation,  to 
a  firm  bearing  upon  the  washers  beneath  them,  the  ad- 
justable ring  will  be  fastened  so  as  for  many  years  to  need 
no  further  adjustment. 

"When  this  has  been  completed,  the  thin  brass  ferule  is 
slipped  over  the  outside  ring,  concealing  the  screw  heads, 
and  avoiding  the  danger  of  their  disturbance  by  an  inexpe- 
rienced operator. 

In  effecting  this  adjustment,  it  is  always  best  to  bring  the 
•wires  into  the  centre  of  the  field  of  view,  by  moving  the 
little  screws  A  A  (fig.  21)  working  in  the  ring  which 
embraces  the  eye-piece  tube. 

Should  the  engineer  desire  to  make  this  adjustment,  it 
will  be  necessary  to  remove  the  bubble  tube,  in  order  that 
the  small  screw  immediately  above  its  scale  may  be  operated 
upon  with  the  screw-driver. 

The  adjustment  we  have  now  given  is  preparatory  to 
those  which  follow,  and  are  common  to  all  leveling  instru- 
ments of  recent  construction,  and  are  all  that  the  engineer 

8 


114 


THE  LEVELING  INSTRUMENT. 


will  have  to  do  with,  in  using  our  own  instruments.  What 
is  still  necessary  then  is — 

1.  To  adjust  the  line  of  coUimation,  or  in  other  words,  to 
bring  both  wires  into  the  optical  axis,  so  that  their  point  of 
intersection  will  remain  on  any  given  point,  during  an  entire 
revolution  of  the  telescope. 

2.  To  bring  the  level  bubble  parallel  with  the  bearings  of  the 
T  rings,  and  with  the  longitudinal  axis  of  the  telescope. 

3.  To  adjust  the  wyes,  or  to  bring  the  bubble  into  a 
position  at  right  angles  to  the  vertical  axis  of  the  instru- 
ment. 

To  Adjust  the  Line  of  Collimation,  set  the  tripod  firmly, 
remove  the  Y  pins  from  the  clips,  so  as  to  allow  the  tele- 
scope to  turn  freely,  clamp  the  instrument  to  the  tripod 
head,  and,  by  the  leveling  and  tangent  screws,  bring  either 
of  the  wires  upon  a  clearly  marked  edge  of  some  object, 
distant  from  one  to  five  hundred  feet. 

Then  with  the  hand  carefully  turn  the  telescope  half 
way  around,  so  that  the  same  wire  is  compared  with  the 
object  assumed. 

Should  it  be  found  above  or  below,  bring  it  half  way  back 
by  moving  the  capstan  head  screws  at  right  angles  to  it, 
remembering  always  the  inverting  property  of  the  eye-piece ; 
now  bring  the  wire  again  upon  the  object,  and  repeat  the 
first  operation  until  it  will  reverse  correctly. 

Proceed  in  the  same  manner  with  the  other  wire  until  the 
adjustment  is  completed. 

Should  both  wires  be  much  out,  it  will  be  well  to  bring 
them  nearly  correct  before  either  is  entirely  adjusted. 

When  this  is  effected,  slip  off  the  covering  of  the  eje^ 
piece  centering  screws,  shown  in  the  sectional  view  (fig.  21) 
at  A  A,  and  move  each  pair  in  succession  with  a  small  screw- 
driver, until  the  wires  are  brought  into  the  centre  of  the 
field  of  view. 


THE  LEVELING  INSTRUMENT. 


115 


The  inversion  of  the  eye-piece  does  not  affect  this  opera- 
tion, and  the  screws  are  moved  direct. 

To  test  the  correctness  of  the  centering,  revolve  the  tele- 
scope, and  observe  whether  it  appears  to  shift  the  position 
of  an  object. 

Should  any  movement  be  perceived,  the  centering  is  not 
perfectly  effected. 

It  may  here  be  repeated,  that  in  all  telescopes  the  position 
and  adjustment  of  the  line  of  collimation  depends  upon 
that  of  the  object-glass ;  and,  therefore,  that  the  movement 
of  the  eye-piece  does  not  effect  the  adjustment  of  the  wires 
in  any  respect. 

When  the  centering  has  been  once  effected  it  remains  per- 
manent, the  cover  being  slipped  over  to  conceal  and  protect 
it  from  derangement  at  the  hands  of  the  curious  or  inexpe- 
rienced operator. 

To  Adjust  the  Level  Bubble. — Clamp  the  instrument 
over  either  pair  of  leveling  screws,  and  bring  the  bubble 
into  the  centre  of  the  tube. 

Now  turn  the  telescope  in  the  wyes,  so  as  to  bring  the 
level  tube  on  either  side  of  the  centre  of  the  bar.  Should 
the  bubble  run  to  the  end  it  would  show  that  the  vertical 
plane,  passing  through  the  centre  of  the  bubble,  was  not 
parallel  to  that  drawn  through  the  axis  of  the  telescope 
rings. 

To  rectify  the  error,  bring  it  by  estimation  half  way  back, 
with  the  capstan  head  screws,  which  are  set  in  either  side 
of  the  level  holder,  placed  usually  at  the  object  end  of  the 
tube. 

Again  bring  the  level  tube  over  the  centre  of  the  bar,  and 
adjust  the  bubble  in  the  centre,  turn  the  level  to  either  side, 
and,  if  necessary,  repeat  the  correction  until  the  bubble  will 
keep  its  position,  when  the  tube  is  turned  half  an  inch  or 
more,  to  either  side  of  the  centre  of  the  bar. 


116 


THE  LEVELING  INSTRUMENT. 


The  necessity  for  this  operation  arises  from  the  fact,  that 
when  the  telescope  is  reversed  end  for  end  in  the  wyes  in 
the  other  and  principal  adjustment  of  the  bubble,  we  are 
not  certain  of  placing  the  level  tube  in  the  same  vertical 
plane ;  and,  therefore,  it  would  be  almost  impossible  to 
effect  the  adjustment  without  a  lateral  correction. 

Having  now,  in  great  measure,  removed  the  preparatory 
difficulties,  we  proceed  to  make  the  level  tube  parallel  with 
the  bearings  of  the  Y  rings. 

To  do  this,  bring  the  bubble  into  the  centre  with  the 
leveling  screws,  and  then,  without  jarring  the  instrument, 
take  the  telescope  out  of  the  wyes  and  reverse  it  end  for 
end.  Should  the  bubble  run  to  either  end,  lower  that  end, 
or  what  is  equivalent,  raise  the  other  by  turning  the  small 
adjusting  nuts,  on  one  end  of  the  level,  until  by  estima- 
tion half  the  correction  is  made ;  again  bring  the  bubble 
into  the  centre  and  repeat  the  whole  operation,  until  the 
reversion  can  be  made  without  causing  any  change  in 
the  bubble. 

It  would  be  well  to  test  the  lateral  adjustment,  and  make 
such  correction  as  may  be  necessary  in  that,  before  the 
horizontal  adjustment  is  entirely  completed. 

To  Adjust  the  Wyes. — Having  effected  the  previous  ad- 
justments, it  remains  now  to  describe  that  of  the  wyes,  or, 
more  precisely,  that  which  brings  the  level  into  a  position 
at  right  angles  to  the  vertical  axis,  so  that  the  bubble  will 
remain  in  the  centre  during  an  entire  revolution  of  the 
instrument. 

To  do  this,  bring  the  level  tube  directly  over  the  centre 
of  the  bar,  and  clamp  the  telescope  firmly  in  the  wyes, 
placing  it  as  before,  over  two  of  the  leveling  screws,  un- 
clamp  the  socket,  level  the  bubble,  and  turn  the  instrument 
half  way  around,  so  that  the  level  bar  may  occupy  the  same 
position  with  respect  to  the  leveling  screws  beneath. 


THE  LEVELING  INSTRUMENT. 


117 


Should  the  bubble  run  to  either  end,  bring  it  half  way 
back  by  the  Y  nuts  on  either  end  of  the  bar  ;  now  move  the 
telescope  over  the  other  set  of  leveling  screws,  bring  the 
bubble  again  into  the  centre,  and  proceed  precisely  as  above 
described,  changing  to  each  pair  of  screws,  successively, 
until  the  adjustment  is  very  nearly  perfected,  when  it  may 
be  completed  over  a  single  pair. 

The  object  of  this  approximate  adjustment,  is  to  bring  the 
upper  parallel  plate  of  the  tripod  head  into  a  position  as 
nearly  horizontal  as  possible,  in  order  that  no  essential 
error  may  arise,  in  case  the  level,  when  reversed,  is  nob 
brought  precisely  to  its  former  situation.  When  the  level 
has  been  thus  completely  adjusted,  if  the  instrument  is 
properly  made,  and  the  sockets  well  fitted  to  each  other 
and  the  tripod  head,  the  bubble  will  reverse  over  each  pair 
of  screws  in  any  position. 

Should  the  engineer  be  unable  to  make  it  perform  cor- 
rectly, he  should  examine  the  outside  socket  carefully  to 
see  that  it  sets  securely  in  the  main  socket,  and  also 
notice  that  the  clamp  does  not  bear  upon  the  ring  which 
it  encircles. 

When  these  are  correct,  and  the  error  is  still  manifested, 
it  will,  probably,  be  in  the  imperfection  of  the  interior 
spindle. 

After  the  adjustments  of  the  level  have  been  effected,  and 
the  bubble  remains  in  the  centre,  in  any  position  of  the 
socket,  the  engineer  should  carefully  turn  the  telescope  in 
the  wyes,  and  sighting  upon  the  end  of  the  level,  which  has 
the  horizontal  adjustments  along  each  side  of  the  wye,  make 
the  tube  as  nearly  vertical  as  possible. 

When  this  has  been  secured,  he  may  observe,  through 
the  telescope,  the  vertical  edge  of  a  building,  noticing  if 
the  vertical  hair  is  parallel  to  it ;  if  not,  he  should  loosen 
two  of  the  crosswire  screws  at  right  angles  to  each  other 


118 


THE  LEVELING  INSTRUMENT. 


and  witli  the  hand  on  these,  turn  the  ring  inside,  until 
the  hair  is  made  vertical;  the  line  of  colhmation  must 
then  be  corrected  again,  and  the  adjustments  of  the  level 
will  be  complete. 

To  use  the  Level, 

When  using  the  instrument,  the  legs  must  be  set  firmly 
into  the  ground,  and  neither  the  hands  nor  person  of  the 
operator  be  allowed  to  touch  them  ;  the  bubble  should  then 
be  brought  over  each  pair  of  leveling  screws  successively, 
and  leveled  in  each  position,  any  correction  being  made  in 
the  adjustments  that  may  appear  necessary. 

Care  should  be  taken  to  bring  the  wires  precisely  in 
focus,  and  the  object  distinctly  in  view,  so  that  all  errors  of 
parallax  may  be  avoided. 

This  error  is  seen  when  the  eye  of  an  observer  is  moved 
to  either  side  of  the  centre  of  the  eye-piece  of  a  telescope, 
in  which  the  foci  of  the  object  and  eye-glasses  are  not 
brought  precisely  upon  the  cross-wires  and  object ;  in  such 
a  case  the  wires  will  appear  to  move  over  the  surface,  and 
the  observation  will  be  liable  to  inaccuracy. 

In  all  instances  the  wires  and  object  should  be  brought 
into  view  so  perfectly,  that  the  spider  lines  will  appear  to 
be  fastened  to  the  surface,  and  will  remain  in  that  position 
however  the  eye  is  moved. 

If  the  socket  of  the  instrument  becomes  so  firmly  set  in 
the  tripod  head  as  to  be  difficult  of  removal  in  the  ordinary 
way,  the  engineer  should  place  the  palm  of  his  hand  under 
the  Vv^ye  nuts  at  each  end  of  the  bar,  and  give  a  sudden 
upward  shock  to  the  bar,  taking  care  also  to  hold  his  hands 
so  as  to  grasp  it  the  moment  it  is  free. 


Emu.  D.  t;f:nson.  tit 


THE  BUILDERS  LEVEL.  il9 

Weight  of  Leveling  Instruvients. 
The  average  weights  of  the  different  sizes  ot  this  instru- 
ment, exclusive  of  the  tripod  legs,  are  as  follows  : 

16-inch  telescope  11|  lbs. 

18-inch      do  12  do. 

20-inch      do  121  do. 

22-inch      do  13  do. 


THE  BUILDER'S  LEVEL. 

This  instniment,  shown  in  the  engraving,  is  of  much 
more  simple  and  compact  construction  than  those  already 
described- 
It  has  a  telescope  of  from  eleven  to  twelve  inches  long, 
provided  with  the  usual  facilities  for  adjustment,  resting 
upon  the  ends  of  the  bar  by  two  similar  faces  of  the  octagonal 
shaped  prisms,  which  surround  the  tube  at  either  end. 

The  telescope  is  held  on  the  bar  by  a  stout  screw  at  each 
end  ;  the  heads  of  these  screws  are  shown  on  the  imder  side 
of  the  bar,  and  are  bored  to  admit  the  usual  adjusting  pin. 

A  strong  spiral  spring  is  placed  in  a  recess  in  the  upper 
side  of  each  end  of  the  bar,  and  serves,  in  connecticm  with 
the  screws,  to  effect  the  third  adjustment  of  the  Level. 

These  springs  are  of  course  removed  while  the  other 
adjustments  are  in  progress,  and  the  telescope  allowed  to 
rest  directly  upon  the  bar. 

The  level  is  placed  above  the  telescope,  and  adjustable  at 
either  end  by  two  nuts,  as  shown. 

The  instrument  is  best  used  upon  the  adjusting  tripod, 
as  represented,  but  may  also  be  placed  upon  a  simple  ball 
spindle,  and  used  in  connection  with  the  leveling  socket, 
shown  in  our  account  of  the  Solar  Compass. 

The  adjustments  of  this  instrument  are  made  in  the  same 
order,  and  almost  precisely  in  the  same  manner,  as  those  of 


T  20  THE  DFMPY.  OR  BUILDER  S  LEVEL. 


the  Engineers'  Level,  depcribed  op  pages  114-118,  and  need 
but,  a  brief  description. 

To  adjust  the  line  of  coUimation,  it  is  necessary  first  to 
remove  the  level  and  the  small  nuts  which  attach  it  to  the 
screw  wires  or  stems  fixed  in  the  top  of  the  prisms ;  then 
the  telescope  can  be  detached  from  the  bar  by  taking  out 
the  capstan  head  screws,  shown  on  the  under  side  of  the 
bar,  and  also  the  steel  springs  on  the  upper  side. 

(1.)  The  Hne  of  coUimation  is  then  adjusted  like  that  of 
the  ordinary  Y  level,  by  making  the  cross  wires  to  reverse 
upon  any  given  point  when  the  telescope  is  turned  haK  way 
around,  so  as  to  rest  upon  the  bar  by  the  opposite  faces  of 
the  prisms. 

(2.)  The  Level  is  adjusted  by  turning  the  telescope  end 
for  end  upon  the  bar,  the  bubble  being  made  to  come  to  the 
centre  in  both  positions. 

(3.)  The  bubble  is  brought  into  a  position  at  right  angles 
to  the  vertical  axis  (the  adjustment  of  the  wyes  in  ordinary 
levels),  by  releasing  or  compressing  the  springs  at  the  ends 
of  the  bar,  so  that  the  bubble  will  come  into  the  centre,  as 
the  instrument  is  turned  upon  its  spindle,  over  both  pairs 
of  leveling  screws  in  succession. 

The  weight  of  this  level,  with  adjusting  tripod,  excluding 
the  tripod  legs,  is  less  than  four  pounds. 


THE  AMERICAN  DUMPY,  OR  BUILDER'S  LEVEL. 

FIFTEEN-INCH  TELESCOPE. 

We  have  frequently  been  desired  to  furnish  a  level 
simpler  and  cheaper  in  construction  than  the  usual  Y  Level, 
and  yet  capable  of  doing  accurate  work,  and  with  superior 
telescope,  &c. 

We  have,  therefore,  introduced  our  new  Builder's  Level, 
having  a  telescope  as  powerful  as  that  of  the  eigh teen-inch 


m>  IMCH  TELESCOPE 


Made  hy 


T. 


3£A/^.  D.  B/rA/SO*J. 


LEVELING  RODS. 


121 


T  Level,  and  made  larger  and  more  substantial  than  the 
instrument  before  described. 

Our  fifteen-inch  Level  has,  we  believe,  all  the  advantages  of 
compactness  and  portability  of  the  English  dumpy  level — and, 
besides,  the  facihty  of  adjustment  of  the  American  Y  Level. 

The  adjustments  of  this  instrument  are  the  same  as  those 
of  the  instrument  just  before  described,  and  it  is  used  pre- 
cisely like  the  Y  Level. 


LEVELING  KODS. 
The  two  kinds  most  generally  used  by  American  engineers, 
are  both  sliding  rods,  divided  into  hundredths  of  a  foot,  and 
reading  by  verniers  to  thousandths. 

Boston  Rod. 

That  known  as  the  Boston  or  Yankee  Eod,  is  formed  of 
two  pieces  of  light  baywood  or  mahogany,  each  about  six 
and  a  half  feet  long,  connected  together  by  a  tongue,  and 
sliding  easily  by  each  other,  in  both  directions. 

One  side  is  furnished  with  a  clamp  screw  and  vernier  at 
each  end,  the  other  carries  the  divisions,  marked  on  strips 
of  satin  wood,  inlaid  on  either  side. 

The  target  is  a  rectangle  of  wood,  fastened  near  one  end 
of  the  divided  side,  and  having  its  horizontal  line  just 
three-tenths  from  the  extremity. 

The  target  being  fixed,  when  any  height  is  taken  above 
six  feet,  the  rod  is  changed  end  for  end,  and  the  divisions 
read  by  the  other  vernier  ;  the  height  to  which  the  rod  can 
be  extended  being  a  little  over  eleven  feet. 

This  kind  of  rod  is  very  convenient  from  its  great  light- 
ness, but  the  parts  are  made  too  frail  to  endure  the  rough 
usage  of  this  country,  and,  therefore,  American  engineers 
have  generally  given  the  preference  to  another,  made  heavier 
and  more  substantial. 


LEVELING  RODS. 


The  New  York  Rod, 

This  rod,  which  is  shown  in  the  engraving, 
as  cut  in  two,  so  that  the  ends  may  be  exhi- 
bited, is  made  of  satin  wood,  in-  two  pieces 
like  the  former,  but  sliding  one  from  the  other, 
the  same  end  being  always  held  on  the  ground, 
and  the  graduations  starting  from  that  point. 

The  graduations  are  made  to  tenths  and  hun- 
dredths of  a  foot,  the  tenth  figures  being  black, 
and  the  feet  marked  with  a  large  red  figure. 

The  front  surface,  on  which  the  target 
moves,  reads  to  six  and  a  half  feet;  when  a 
greater  height  is  required,  the  horizontal  line 
of  the  target  is  fixed  at  that  point,  and  the 
upper  half  of  the  rod,  carrying  the  target,  is 
moved  out  of  the  lower,  the  reading  being  now 
obtained  by  a  vernier  on  the  graduated  side, 
up  to  an  elevation  of  twelve  feet. 

The  mountings  of  this  rod  are  differently 
made  by  different  manufacturers.  We  shall 
give  those  which  we  have  adopted. 

The  target  is  round,  made  of  thick  brass, 
having,  to  strengthen  it  still  more,  a  rib  raised 
on  the  edge,  which  also  protects  the  paint 
from  being  defaced. 

The  target  moves  easily  on  the  rod,  being 
kept  in  any  position  by  the  friction  of  the  two 
flat  plates  of  brass  which  are  pressed  against 
two  alternative  sides,  by  small  spiral  springs, 
working  in  little  thimbles  attached  to  the  band 
which  surrounds  the  rod. 

There  is  also  a  clamp  screw  on  the  back,  by 
which  it  may  be  securely  fastened  to  any  part 
of  the  rod. 


Made  by 


BiNJ.D.BEi'JSON,  N Ev,'.  YORK. 


THE  miner's  compass. 


123 


The  face  of  the  target  is  divided  into  quadrants,  by  hori- 
zontal and  vertical  diameters,  which  are  also  the  boundaries 
of  the  alternate  colors  with  which  it  is  painted. 

The  colors  usually  preferred  are  white  and  red :  some- 
times white  and  black. 

The  opening  in  the  face  of  the  target  is  a  little  more  .than 
a  tenth  of  a  foot  long,  so  that  in  any  position  a  tenth,  or  a 
foot  figure,  can  be  seen  on  the  surface  of  the  rod. 

The  right  edge  of  the  opening  is  chamfered,  and  divided 
into  ten  equal  spaces,  corresponding  with  nine  hundredths 
on  the  rod;  the  divisions  start  from  the  horizontal  line 
which  separates  the  colors  of  the  face. 

The  vernier,  like  that  on  the  other  side  of  the  rod,  reads 
to  thousandths  of  a  foot. 

The  clamp,  which  is  screwed  fast  to  the  lower  end  of  the 
upper  sliding  piece,  has  a  movable  j)art  which  can  be 
brought  by  the  clamp  screw  firmly  against  the  front  surface 
of  the  lower  half  of  the  rod,  and  thus  the  two  parts 
immovably  fastened  to  each  other  without  marring  the 
divided  face  of  the  rod. 


THE  MINER'S  COMPASS. 
This  instrument,  shown  in  the  engraving,  consists  essen- 
tially of  a  magnetic  needle  so  suspended  as  to  move  readily 
in  a  vertical  direction,  the  angle  of  inclination,  or  ''dip," 
being  measured  upon  the  divided  rim  of  a  small  compass 
box. 

When  in  use,  the  ring  or  bail  is  held  in  the  hand — the 
compass  box  by  its  own  weight  takes  a  vertical  position — • 
and  should  also  be  in  the  plane  of  the  magnetic  meridian. 

In  this  position  the  needle,  when  unaffected  by  the 
attraction  of  iron,  assumes  a  horizontal  line,  as  shown  by 
the  zeros  of  the  circle.    When  brought  over  any  mass  of 


124 


THE  POCKET  COMPASS. 


iron  it  dips,  and  thus  detects  the  presence  of  iron  ores  with 
certainty. 

If  the  compass  box  is  held  horizontally,  it  serves  as  an 
ordinary  pocket  compass.  The  box  of  the  Miner's  Compass 
is  often  made  of  brass,  with  a  cover  of  the  same  material. 
The  best  form,  however,  we  believe  to  be  that  shown  in  the 
engraving,  having  its  two  sides  of  glass,  and  provided  also 
with  a  stop  for  the  needle,  worked  by  the  little  brass  knob, 
there  shown. 

This  Compass  is  packed  in  a  small  mahogany  case,  and 
used  as  above  described,  the  observer  standing  with  his  face 
to  the  west,  and  holding  the  compass  box  suspended  in  the 
plane  of  the  magnetic  meridian. 


THE  POCKET  COMPASS. 
Fig.  26. 


This  little  instrument,  shown  with  jacob-stafif  socket  in 
fig.  26,  though  not  used  in  extensive  surveys  like  the  larger 
compasses  we  have  described,  is  found  very  convenient  in 
making  explorations,  or  in  retracing  the  lines  of  govern- 
ment surveys,  as  in  locating  land  warrants,  &c. 

The  sights  are  made  with  a  slote  and  a  hair,  on  opposite 
sides ;  they  also  have  joints  near  the  base,  so  as  to  fold  over 


BEr^J .  D .  BENSON,  NE  W  YORK. 


THE  POCKET  COMPASS. 


125 


eacli  other  above  the  glass,  when  the  compass  is  packed  in 
its  case. 

The  circle  is  graduated  to  degrees,  and  figured  from  0  to 
90  each  way,  as  in  larger  instruments. 

The  needle  is  suspended  upon  a  jeweled  centre,  and  is 
raised  by  the  lifter  shown  in  the  cut. 

The  jacob-staff  socket  is  often  used  with  the  compass, 
being  screwed  to  the  under  side,  and  detached  at  pleasure. 

The  mountings  are  all  that  are  furnished,  the  staff  itself 
being  easily  made  out  of  a  common  walking-stick. 

We  make  two  sizes  of  the  Pocket  Compass,  differing 
mainly  in  the  needle,  which  in  one  is  two  and  a  half,  in  the 
other  three  and  a  half  inches  long. 

The  larger  size  is  also  sometimes  provided  with  two  small 
levels,  let  into  the  face  of  the  compass  ;  these  are  not  shown 
in  the  cut. 


VEENIEE  POCKET  COMPASS. 
This  instrmnent,  shown  in  the  engraving,  has  also  a 
three  and  a  half  inch  needle,  and  is  furnished  with  a  vernier 
outside,  reading  to  five  minutes,  by  which  the  sights  can  be 
placed  at  any  desired  angle  with  the  line  of  zeros,  so  as  to 
set  off  the  variation  of  the  needle,  as  with  the  Vernier 
Compass. 

The  compass  is  furnished  with  jacob-staff  mountings ; 
sometimes,  if  desired,  with  a  very  light  tripod,  as  shown  in 
the  engraving ;  has  two  levels,  and  is  neatly  packed  in  a 
mahogany  case. 

It  makes  a  most  excellent  and  portable  little  instrument 
in  locations,  and  is  especially  useful  for  the  surveyor  of 
government  lands. 


126 


TRIPODS. 


Greneral  ]M]atters. 


TRIPODS. 

In  the  tripods  of  all  our  instruments,  the  upper  part  of  the 
leg,  is  flattened,  and  fitted  closely  in  the  surfaces  of  the 
brass  cheek  pieces. 

The  cheeks  are  made  very  broad,  and  give  a  firm  hold 
upon  the  leg,  which  may  be  tightened  at  any  time  by  screw- 
ing up  the  bolts  which  pass  through  the  top  of  the  legs  ; 
this  is  especially  necessary  after  the  surface  of  the  wood 
has  been  much  worn. 

The  legs  are  round,  and  taper  in  each  direction  from  a 
swell,  turned  about  one- third  the  way  down,  from  the  head 
to  the  point. 

The  point,  or  shoe,  is  a  tapering  brass  ferule,  having  an 
iron  end  ;  it  is  cemented,  and  riveted  firmly  to  the  wood. 

The  legs  of  all  our  tripods  are  about  four  feet  eight  inches 
long,  from  head  to  point.  We  make  three  sizes  of  tripods, 
which  we  will  now  separately  describe. 

1.  The  Compass  Tripod,  seen  in  part  in  the  cut  of  the 
vernier  transit,  and  having  the  brass  plate  to  which  the 
cheeks  are  attached,  three  and  three-fourth  inches  in  diameter, 
and  legs  which  are  about  one  inch  at  the  top,  one  and  three- 
eighths  at  the  swell,  and  seven-eighths  at  the  bottom. 

The  legs  are  usually  made  of  cherry,  sometimes  of  maho- 
gany, and  the  tripod  is  used  with  the  various  kinds  of  com- 
passes, and  with  the  vernier  transit. 

2.  The  Medium  Sized  Tripod,  shown  with  the  surveyor's 
transit,  and  having  a  plate  of  same  diameter  as  above,  but 


TRIPODS. 


127 


'with  the  checks  made  considerably  broader,  by  curving  at 
each  end  ;  the  legs  being  also  about  an  eighth  of  an  inch 
larger  throughout. 

This  tripod  has  mahogany  legs,  and  is  used  with  the 
surveyor's  transit,  the  light  engineer's  transit,  and  the  six- 
teen inch  level. 

3.  The  Heavy  Tkipod,  shown  with  the  engineer's  transit, 
having  a  brass  plate  of  four  and  one-fourth  inches  diameter, 
with  extended  cheek  pieces,  and  with  legs  one  and  three- 
eighths  of  an  inch  at  the  top,  one  and  three-fourths  at  the 
swell,  and  one  and  an  eighth  at  the  point. 

The  heavy  size  has  also  mahogany  legs,  and  is  used  with 
the  engineer's  transit,  and  larger  leveling  instruments. 

Lacquering. 

All  instruments  are  covered  with  a  thin  varnish,  made  by 
dissolving  gum  shellac  in  alcohol,  and  applied  when  the 
work  is  heated. 

As  long  as  this  varnish  remains,  the  brass  surface  will  be 
kept  from  tarnishing,  and  the  engineer,  by  taking  care  not 
to  rub  his  instrument  with  a  dusty  cloth,  or  to  expose  it 
to  the  friction  of  his  clothes,  can  preserve  its  original  iresh- 
ness  for  a  long  time. 

Bronze  Finish. 

Instead  of  the  ordinary  brass  finish,  some  engineers  prefer 
Instruments  blackened  or  bronzed.  This  is  done  with  an 
acid  preparation,  after  the  work  has  been  polished,  and  gives 
the  instrument  a  very  showy  appearance,  besides  being 
thought  advantageous  on  account  of  not  reflecting  the  rays 
of  the  sun  as  much  as  the  ordinary  finish. 

When  well  lacquered,  the  bronzing  will  last  a  considerable 
time,  but  as  soon  as  it  becomes  a  little  worn  the  appearance 
of  the  instruirent  is  much  worse  than  one  finished  in  the 
usual  style. 


128 


CHAINS. 


CHAINS. 

Surveyors'  Chains. 

Four  Pole  Chains. — The  ordinary  surveyor's  chain  is 
sixty-six  feet,  or  four  poles  long,  composed  of  one  hun- 
dred links,  each  connected  to  the  other  by  two  rings,  and 
furnished  with  tally  marks  at  the  end  of  every  ten  links. 

In  all  the  chains  we  manufacture,  the  rings  are  oval,  are 
sawed,  and  well  closed,  the  ends  of  the  wire  forming  the  hook 
being  also  filed  and  bent  close  to  the  link,  so  as  to  avoid  the 
danger  of  kinking." 

A  link  in  measurement  includes  a  ring  at  each  end. 

The  handles  are  of  brass,  and  each  forms  part  of  the  end 
links,  to  which  it  is  connected  by  a  nut,  by  which  also  the 
length  of  the  chain  is  adjusted. 

The  tallies  are  also  of  brass,  and  have  one,  two,  three,  or 
four,  notches,  as  they  are  ten,  twenty,  thirty,  or  forty,  liuks, 
from  either  end  ;  the  fiftieth  link  is  rounded,  so  as  to  dis- 
tinguish it  from  the  others. 

Two  Pole  Chains. — In  place  of  the  four  pole  chain  just 
described,  many  survej^ors  prefer  one  of  two  rods  or  thirty- 
three  feet  long,  having  but  fifty  links,  and  counted  by  ita 
tallies  from  one  end  in  a  single  direction. 

Snap  for  Altering  Chains. — We  often  make  four  pole 
chains  so  arranged,  that  by  detaching  a  steel  snap  in  the 
middle,  the  two  parts  can  be  separated,  and  then  oije  of  the 
handles  being  removed  in  the  same  manner,  and  transferred 
to  the  forty-ninth  link,  a  two  pole  chain  is  readily  obtained. 
This  modification  is  made  whenever  desired,  and  without  any 
additional  charge. 


CHAINS. 


129 


Sizes  of  Wire. — Our  surveyors'  chains  are  made  of  the 
best  refined  iron  wire,  of  sizes  No.  8  or  10,  as  may  be  pre- 
ferred ;  the  diameter  of  No.  10  wire  being  about  one- 
eighth  of  an  inch,  and  that  of  No.  8  wire  nearly  a  sixteenia 
larger. 

Engineers^  Chains 

Differ  from  the  preceding,  in  that  the  links  are  each  12 
inches  long ;  the  wire,  also,  is  usually  much  stronger. 

They  are  either  fifty  or  one  hundred  feet  long,  and  are 
furnished  with  handles,  tallies,  &c,,  and  sometimes  with  a 
swivel  in  the  middle  to  avoid  being  twisted  in  use. 

In  place  of  the  round  rings  commonly  made,  we  have 
substituted  in  these,  and  our  other  chains,  rings  of  an  oval 
form,  and  find  them  almost  one-tliird  stronger,  though  made 
of  the  same  kind  of  wire. 

Sizes  of  Wire. — The  wire  used  for  these  chains  is  com- 
monly of  No.  5  or  6  ;  the  first  being  nearly  one-fourth  of  an 
inch  in  diameter,  while  No.  6  wire  is  about  one-sixteenth 
smaller. 

The  wire  is  of  the  first  quality,  and  the  whole  chain  ia 
made  in  the  most  accurate  and  substantial  manner. 

Steel  Chains. 

Chains  made  of  steel  wire,  though  more  costly  than  those 
which  we  have  just  described,  are  yet  often  preferred  on 
account  of  their  greater  lightness  and  strength. 

They  are  made  of  any  desired  size  or  length,  generally 
of  No,  10,  rarely  of  No.  8  wire,  and  are  very  stiff  and 
strong. 

Brazed   Steel  Chains. — A  very  portable  and  excellent 
measure  is  made,  by  a  light  steel  chain,  each  link  and  ring 
of  which  is  securely  brazed^  after  being  united  together  ana 
tested  the  wire  is  also  tempered. 
9 


130 


CHAINS. 


The  wire  generally  used  by  us  is  of  size  No.  12,  tlie  rings 
are  of  oval  form,  the  chain,  though  exceedingly  light,  is 
almost  incapable  of  being  either  broken  or  stretched. 

Our  steel  brazed  chains  have  been  found  exceedingly 
desirable  for  all  kinds  of  measurement,  and  for  the  use  of 
engineers  upon  railroads  and  canals  have  almost  entirely 
superseded  the  heavier  chains. 

Grumman's  Patent  Chains, 
These  chains,  invented  and  patented  by  J.  M.  Grumman, 
of  Brooldyn,  N.  Y.,  are  made  of  very  light  steel  wire,  the 
links  being  finely  tempered,  and,  as  shown  in  the  illustration. 


BO  formed  at  the  ends  as  to  fold  together  readily,  and  thus 
dispense  with  the  use  of  rings. 

This  construction  gives  only  one-third  as  many  wearing 
points  as  the  ordinary  chain,  and  affords  the  utmost  facility 
for  repairs,  from  five  to  ten  extra  links  being  furnished  with 
each  chain,  vfhich  have  only  to  be  sprung  into  place  to  replace 
such  as  may  have  been  broken ;  it  can  also  be  taken  apart 
at  any  link,  and,  by  having  a  spring-catch  on  either  handle, 
be  made  of  any  length  desired.  These  chains  are  made  of 
three  different  sizes  of  wire — the  first  two,  termed  drag  chains, 
being  of  size  No.  12  and  15,  and  used  for  measuring  on  the 
surface,  like  the  ordinary  chain  ;  and  the  second,  called  the 
"  suspended  chain,"  for  very  accurate  measurements,  made 
of  No.  18  wire,  and  with  spring-balance,  thermometer  and 


CHAINS. 


131 


spirit  level  attachments,  to  be  held  above  the  surface  when  in 
use,  the  extremities  of  the  chain  being  marked  upon  the 
ground  by  the  points  of  plummets  let  fall  from  the  ends  of 
tlie  chain. 

The  drag-chains  are  all  that  are  needed  in  common  land 
surveys  ;  for  a  mixed  practice  of  village  and  country  survey- 
ing, the  spring-balance  should  be  attached  to  the  drag- 
chains,  while  for  city  surveying  the  suspended  chain,  with 
all  its  attachments,  is  the  proper  instrument. 

A  more  complete  description  of  these  chains,  and  of  chain 
measurements  in  general,  written  by  the  inventor,  will  be 
sent  by  us  to  any  one  applying  for  the  same. 

We  have  purchased  the  patent  for  the  Grumman  chains, 
with  the  entire  right  to  make  and  sell  them,  and  shall  here- 
after be  able  to  furnish  them  promptly. 

Marhing  Fins. 

In  chaining,  there  are  needed  ten  marking  pins,  or  chain 
stakes,  made  either  of  iron,  steel,  or  brass  wire,  as  may  be 
pjref erred,  about  fourteen  inches  long,  pointed  at  one  end  to 
enter  the  ground,  and  formed  into  a  ring  at  the  other,  for 
convenience  in  handling. 

They  are  sometimes  loaded  with  a  little  mass  of  lead 
around  the  lower  end,  so  as  to  answer  as  a  plumb  when 
dropped  to  the  ground,  from  the  suspended  end  of  the 
chain. 

To  use  the  Chain. 
In  using  the  chain  its  length  must  be  taken  from  its 
extreme  ends,  and  the  pins  placed  on  the  outside  of  the 
handles  ;  it  must  be  drawn  straight  and  taut,  and  care- 
fully examined  to  detect  any  kinks  or  other  causes  of 
inaccuracy. 

Our  chains  are  all  carefully  tested  at  every  ten,  some- 


132 


TAPE  MEASURES, 


times  at  every  link,  and  in  their  whole  length  by  the  TJ.  S. 
standard,  and  when  new  may  always  be  relied  upon  as 
correct. 

But  as  all  will  alter,  more  or  less,  after  long  use  in  the 
field,  it  will  be  best  for  the  surveyor  to  carefully  lay  down 
on  a  level  surface  the  exact  length  of  the  chain  when  yet 
new,  marking  also  its  extreme  ends  by  monuments  which 
will  not  be  Hable  to  disturbance. 

He  will  thus  have  a  standard  measure  of  his  own  to 
which  the  chain  can  be  adjusted  from  time  to  time,  and 
again  be  used  with  perfect  confidence. 


TAPE  MEASURES. 

The  best  are  Chesterman's  steel  tapes,  made  of  a  thin 
ribbon  of  steel,  which  is  jointed  at  intervals,  and  wound  up 
in  a  leathern  case,  having  a  folding  handle. 

These  tapes  are  of  all  lengths,  from  thirty-three  to  one 
hundred  feet,  divided  into  inches  and  hnks,  or  more  usually, 
tenths  of  a  foot,  and  links,  the  figures  and  graduations  being 
raised  on  the  surface  of  the  steel. 

The  great  cost  of  the  steel  tape  has  always  prevented  its 
general  use,  and  the  metallic  tape  of  the  same  manufacturer 
is  the  only  one  commonly  employed  in  American  engineering. 

These  are  of  linen,  and  have  also  fine  brass  wires  inter- 
woven through  their  whole  length. 

They  are  thus  measurably  correct,  even  when  wet. 

They  are  mounted  like  the  steel  tapes,  of  hke  lengths, 
and  similarly  graduated. 


SWISS  INSTRUMENTS. 


133 


STipplement  to  Mannal. 


DEAWING  INSTRUMENTS. 

To  guide  the  surveyor  and  engineer  in  the  selection  of 
Drawing  Instruments,  we  here  add  a  detailed  description, 
with  illustrations  and  prices  of  the  separate  pieces,  and 
cases  of  the  different  kinds  in  general  use. 

Those  we  shall  first  mention  are  of  Swiss  manufacture, 
and  are  of  the  finest  quality  and  finish. 

The  Brass  Instruments  are  used  in  Schools  and  elementary 
practice. 

The  fine  German  Silver  Instruments  are  of  the  best 
German  make,  intended  for  Engineers,  Architects,  and 
Machinists : 

S^viss  Drawing  Instruments. 

OF  GERMAN  SILVER,  EXTRA.  FINE  FINISHED. 


Note.— All  prices  for  imported  goods,  including  Drawing  Instru- 
ments, drawing  paper,  metallic  and  steel  tapes,  given  in  this  book,  are 
in  currency,  estimating  gold  at  forty  per  cent,  premium,  and  are  sub- 
ject to  a  discount  corresponding  with  the  decline  of  gold  at  the  date 
of  the  order. 


134 


SWISS  INSTRUMENTS. 


Figure  No.  Price. 
1  A.  Drawing  Compass,  joints  in  legs,  6i  to  7  inches  long,  -with  pen, 

pencil-holder,  needle-point,  lengthening  bar  and  dot.  pen.... $10  50 
1  B.  Drawing  Compass,  6   inches  long,  with   pen,  pencil-holder, 

lengthening  bar  and  needle  point   8  50 

2.  Hair  Spring  Dividers,  5-6  inch   3  25 

3.  Plain  Dividers,  4^  inch   2  00 

3.  Plain  Dividers,  5-6  inch   2  50 

4.  Hair  Dividers,  4^  inch   2  75 


5.  Drawing  Compass,  4  inch,  with  pen,  pencil -holder,  and  needle 

point   6  00 

6.  Proportional  Compass,  with  rack  i   11  00 

7.  Proportional  Compass,  with  full  divisions  for  lines  and  circles. .  13  00 

7.  The  same,  with  Micrometer  screw  ■   14  00 

8.  Beam  Compass,  19-20  inches  long,  in  two  German  Silver  bars...  13  25 

8.  The  same,  20  inches  long,  in  3  German  Silver  bars   15  00 

8.  The  same,  36  do  4  do    18  00 

8.  The  same,  54  do  4  do   22  00 

9.  Triangular  Compass  4  80 

10.  Dotting  Pen   2  60 

11.  Road  Pen,  $2.60  to   3  75 


SWiaS  INSTRUMENTS. 


135 


Figure  No.  Price. 

12.  Pocket  Dividers   $2  60 

13.  Whole  and  Half  Dividers   4  00 

14  A.  Universal  Compass,  with  points  to  shift   7  75 

14  B.  Universal  Compass,  with  points  to  turn   8  50 


15.  Large  Steel  Spring  Dividers,  5  to  6-inch...   3  25 

16.  Small  Steel  Stepping  Dividers,  3^  inches   1  75 

17.  Small  Steel  Compass,  with  pen,     do   •   2  25 

17.  Small  Steel  Bow  Pencil,               do    2  25 

18.  Drawing  Pen,  with  joint,  4i  inches  long   1  50 

19.  do             do        5i        do    1  75 

20.  do            do        6         do    2  00 

21 .  Horn  Centre,  with  German  Silver  frame   45 

22.  Bow  Pen   2  75 

23.  Bow  Pen,  with  pencil-holder   3  50 

24.  German  Silver  Centre,  with  handle   50 

25.  German  Silver  Paper  Pins,  per  dozen   85 

25.       do     Steel         do         do   85 

27.  Eccentric  rule   3  0» 


136 


SWISS  INSTRUMENTS. 


28  28 

Figure  No.  Price. 
28.  Horn  Protractors,  4-inch,  25  cents;  5-incb,  50  cents;  6-inch,  75 

cents;  7-inch   $1  00 

28.  Protractor,  German  Silver,  5^-inch  diameter,  ^  circle,  ^  degrees, 

center  on  outer  edge   2  50 

28.  Protractor,  German  Silver,  6;{-inch  diameter,  ^  circle,  ^  degrees, 

center  on  outer  edge   3  25 

28.  Protractor,  German  Silver,  6|-inch  diameter,  ^  circle,  ^  degrees, 

center  on  outer  edge   4  00 

28.  Protractor,  German  Silver,  5^-inch  diameter,  ^  circle,  ^  degrees, 

center  on  inner  edge   2  75 

28.  Protractor,  German  Silver,  6^-inch  diameter,  ^  circle,  ^  degrees, 

center  on  inner  edge  c   4  50 


29.  Protractor,  German  Silver,  5|-inch  diameter,  whole  circle,  ^  de- 
grees, with  vernier  to  three  minutes     14  00 

29  Protractor,  German  Silver,  8-inch  diameter,  whole  circle,  ^  de- 
grees, vernier  to  1  minute  16  24 


SWISS  INSTRUMENTS, 


137 


Figure  No.  Price. 
29.  Protractor,  German  Silver,  S^-inch  diameter,  I  circle,  i  degrees, 

"with  vernier  reading  to  three  minutes  $11  25 

29.  Protractor,  German  Silver,  8-inch  diameter,  ^  circle,  ^  degrees, 

vernier  reading  to  one  minute   14  60 

29.  Protractor,  German  Silver,  10-inch  diameter,  ^  circle,  ^  degrees, 

vernier  to  one  minute   18  25 

30.  Beam  Compass  furniture,  for  wood  beams,  $7.50;  in  Morocco 

box   8  50 

31.  33  and  34.  Horn  Curves,  each   1  00 

32.  Drawing  Compass,  4  inches,  with  long  ivory  handle,  spring  and 

micrometer,  with  2  pens,  pencil-holder  and  needle  point   7  75 

85.  Parallel  Rule,  with  rollers   3  50 

37  A.  Bow  Compass,  fast  needle  point  and  pen;  joints  in  both  legs..  3  25 
37  B.  Bow  Compass,  fast  needle  point  and  pencil-holder,  with  joints 

in  both  legs   3  25 


C:7*  For  Boxwood  and  Ivory  Scales,  Protractors,  SfC*,  see  pages  147-148. 

Parties  wanting  cases  made  up,  can  select  the  pieces,  and  we  will  have 
boxes  made  to  suit,  at  an  additional  cost  of  from  $7  to  $15,  according  to 
the  size  of  the  boxes,  which  are  made  of  rosewood,  mahogany  or  walnut> 
highly  finished. 


138 


SWISS  INSTRUMENTS. 


CASES  OF  EXTRA  FINE  SWISS  DRAWING  INSTRUMENTS. 

Figure  No.  Price. 

40.  Polished  Walnut  Box,  with  lock  and  key,  and  tray.  Containing: 

Pair  Dividers,  6|  inches  long,  with  pen,  pencil,  and  needle 
points,  and  lengthening  bar;  Pair  plain  Dividers,  5^  inches 
long;  Steel  Bow  Pen,  with  spring;  two  Drawing  Pens,  one  4^ 
inches  long,  and  one  6i  inches  long;  Half  Circle  Protractor,  5 
inches  diameter,  ^  degrees  $23  00 

41.  Same  as  No.  40,  with  the  addition  of  a  pair  of  Dividers,  3^ 

inches  long,  with  pen,  pencil,  and  needle  points,  and  a  Steel 

Bow  Pencil,  with  spring    31  00 

42.  Polished  Rosewood  Box,  with  lock,  and  key,  and  tray.  Contain- 

ing :  Pair  Dividers,  6^  inches  long,  with  pen,  pencil,  and 
needle  points,  and  lengthening  bar;  Pair  Dividers,  Scinches 
long,  with  pen,  pencil,  and  «eedle  points;  Pair  plain  Dividers, 
6|  inches  long;  Pair  Hair  Spring  Dividers,  5^  inches  long; 
Pair  Steel  Spacing  Dividers,  3^  inches  long,  with  spring;  Steel 
Bow  Pen,  with  spring;  Steel  Bow  Pencil,  with  spring;  Three 
Drawing  Pens,  one  4^  inches,  one  5^  inches,  and  one  6  inches 
long;  Half  Circle  Protractor,  6j  inches  diameter,  ^degrees; 
Triangular  Scale  of  Boxwood,  12  inches  long   45  00 

43.  Same  as  No.  42,  with  the  addition  of  a  Pair  of  Proportional  Di- 

viders 9  inches  long,  and  the  Protractor  graduated  in  ^  de- 
grees   60  00 

44.  Polished  Rosewood  Box,  with  lock  and  key,  and  tray.  Contain*- 

ing :  Pair  Dividers,  6^  inches  long,  with  pen,  pencil  and 
needle  points,  and  lengthening  bar;  Pair  Dividers,  3  inches 
long,  with  pen,  pencil,  and  needle  points;  Pair  plain  Dividers, 
6^  inches  long;  Pair  Hair  Spring  Dividers,  5^  inches  long; 
Pair  Proportional  Dividers,  9  inches  long;  Pair  Steel  Spacing 
Dividers,  3^  inches  long,  with  spring;  Steel  Bow  Pen,  with 
spring;  Steel  Bow  Pencil,  with  spring;  Beam  Compass,  21 
inches  long,  with  three  bars;  Three  Drawing  Pens,  one  4| 
inches,  one  5^,  and  one  6^  inches  long;  Railroad  Drawing 
Pen;  Dotting  Pen  ;  Half  Circle  Protractor,  64  inches  diameter, 
^  degrees,  center  on  the  inner  edge ;  Triangular  Scale  of  Box- 
wood, 12  inches  long   85  00 

15.  Polished  Rosewood  Box,  with  lock  and  key,  and  tray;  Pair  Di- 
viders, 6^  inches  long,  with  pen,  pencil,  and  needle  points,  and 
lengthening  bar;  Pair  Dividers,  4  inches  long,  with  ivory 
handle,  adjusting  screw  and  spring,  pencil,  needle  and  two 


MATHEMATICAL  INSTRUMENTS. 


Price* 

pen  points;  Pair  plain  Dividers,  5^  inches  long;  Pair  Hair 
Spring  Dividers,  5^  inches  long;  Pair  Proportional  Dividers, 
9  inches  long,  with  micrometer  adjusting  screw;  Pair  Steel 
Spacing  Dividers,  3^  inches  long,  with  spring;  Pair  Steel 
Spacing  Dividers,  5  inches  long;  Steel  Bow  Pen,  with  spring; 
Steel  Bow  Pencil,  with  spring;  Beam  Compass,  36  inches  long, 
in  4  bars;  Three  Drawing  Pens,  one  4|  inches,  one  5^  inches, 
and  one  6  inches  long;  Railroad  Drawing  Pen,  Dotting  Pen; 
Half  Circle  Protractor,  8  inches  diameter,  with  arm  and  ver- 
nier; Triangular  Scale  of  Boxwood,  12  inches  long  $104  00 


MATHEMATICAL  INSTRUMENTS 

OF  BRASS,  FOR  SCHOOLS. 


Figure  No.  Price. 

1.  Brass  Dividers,  brass  joints,  rivet  heads,  5-inch,  15  cents;  6-inch,  $0  25 
2           do             steel  joints,  screw  heads,  5-inch,  30  cents;  6-inch,  40 

2.  do  brass  joints,  turned  cheeks,  3- inch,  30  cents;  4- 

inch,  40  cents;  5-inch,  50  cents;  6-inch   65 

2.  do  steel  joints,  turned  cheeks,  4-inch,  65  cents;  5- 

inch,  85  cents;  6-inch   1  00 

3.  do            steel  joints,  turned  cheeks,  hair  spring,  5-inch. . .  1  25 

3.  do                   do                do                   do        6-inch...  1  65 

4.  Dividers,  brass,  brass  joints,  turned  cheeks,  4^  inches  long,  with 

pen,  and  pencil  points  and  lengthening  bar,  per  set .... ,   1  68 


140 


DRAWING  INSTRUMENTS. 


Figure  No.  Price. 

Dividers,  brass,  brass  joints,  turned  cheeks,  6  inches  long,  with 

pen  and  pencil  points  and  lengthening  bar,  per  set   $1  25 

5.  Dividers,  brass,  brass  joints,  turned  cheeks,  needle  point,  4^  inches 

long,  with  pen  and  pencil  points  and  lengthening  bar,  per  set,    1  25 

Dividers,  brass,  brass  joints,  turned  cheeks,  needle  point,  6  inches 

long,  with  pen  and  pencil  points  and  lengthening  bar,  per  set,    1  5i) 


6  7  8  9  10 

Dividers,  brass,  medium  quality,  needle  point,  with  pen  and 

pencil  points,  3  inches   75 

Bow  Pen,  brass   75 

Bow  Pen,  brass,  needle  points   75 

Bow  Pen,  brass,  needle  points  and  adjusting  spring   1  00 


ft 


13 


14 


DRAWING  INSTRUMENTS. 


141 


Figure  No.  Price. 

10.  Furniture  for  Beam  Compass,  brass,  with  adjusting  screw,  in 

morocco  case   $6  00 

11.  Bisecting  Dividers,  brass   75 

12.  Proportional  Dividers,  brass,  half  divided  ,    2  50 

13.  Drawing  Pen,  black  handle   35 

Drawing  Pen,  ivory  handle   6C 

14.  Roulette  for  dotting  lines,  with  extra  wheels   1  5C 


CASES  OF  BRASS  DRAWING  INSTRUMENTS 

FOR  SCHOOLS. 


20.  Wood  Box;  pair  4i-inch  Dividers,  with  pen  and  pencil  points, 

and  Crayon  Holder   1  00 

21.  Wood  Box;  pair  4^-inch  Dividers,  with  pen  and  pencil  points 

and  lengthening  bar;  Ebony  handle  Drawing  Pen;  Boxwood 
Scale,  4  inches  long   1  50 


22.  Wood  Box;  Pair  of  4i-inch  Dividers,  with  pen  and  pencil  points 

and  lengthening  bar;  Pair  of  3|-inch  plain  Dividers,  Drawing 
Pen,  Horn  Protractor;  Boxwood  Scale,  4  inches  long   1  75 

23.  Rosewood  Box;  Pair  5^-inch  Dividers,  with  pen  and  pencil  points 

and  lengthening  bar;  Pair  of  4i-inch  plain  Dividers,  Draw- 
ing Pen,  Horn  Protractor;  Box  Wood  Scale,  6  inches  long...,    2  50 

24.  Same  as  23,  with  addition  of  Parallel  Ruler   2  85 

25.  Same  as  23,  with  Ivory  Scale,  6  inches  long   3  00 

26.  Same  as  25,  with  addition  of  Parallel  Ruler   3  3i 


142 


DRAWING  INrtiRUMENTS. 


27  29 

Figure  No.  Price. 

27.  llosewood  Box;  Pair  of  6-inch  Ttviders,  with  pen  and  pencil 

points  and  lengthening  bar;  Tair  of  4^-inch  plain  Dividers, 
Drawing  Pen;  Pair  of  3^-inuh  Dividers,  with  pen  and  pencil 
points;  Brass  Protractor,. Hora  Protractor;  Ivory  Scale,  6  in- 
ches long,  per  set   $4  GO. 

28.  Same  as  No.  27,  but  with  the  instruments  set  in  a  tray,  so  that 

colors,  etc.,  may  be  put  below,  per  set  ....   4  50 

29.  Rosewood  Box;  Pair  of  6-inch  needle  point  Dividers,  with  pen 

and  pencil  points,  and  lengthening  bar;  Pair  4|-inch  plain 
Dividers;  Pair  of  3^-inch  needle  point  Dividers,  with  pen  and 
pencil  points  ;  Drawing  Pen,  Brass  Protractor,  Horn  Protractor; 
Ivory  Scale,  6  inches  long,  per  set   4  75 

30.  Same  as  No.  29,  but  with  lock  and  key  and  the  instruments  set 

in  a  tray,  so  that  the  colors  may  be  put  below,  per  set   5  00 

31.  Same  as  No.  30,  with  addition  of  Parallel  Ruler,  per  set  ......    5  3S 

32.  Rosewood  Box,  with  lock  and  key,  the  instruments  set  in  a  tray, 

so  that  colors,  etc.,  may  be  put  below;  Pair  of  6-inch  needle 
point  Dividers,  with  pen  and  pencil  points,  and  lengthening 
bar;  Drawing  Pen,  Pair  4^-inch  plain  Dividers,  Brass  Protrac- 
tor, Horn  Protractor,  Pair  of  3^-inch  Needle  Point  Dividers, 
with  pen  and  pencil  points;  Spring  Bow  Pen,  with  needle 

point;  Ivory  Scale,  6  inches  long,  per  set   5  75 

83.  Same  as  No.  32,  with  addition  of  Parallel  Ruler,  per  set   6  25 

3i.  Same  as  No.  33,  with  the  addition  of  a  pair  Proportional  Divid- 

erSj  per  set   8  50 


DRAWING  INSTRUMENTS.  143 


FINE  GERMAN  SILVER  INSTRUMENTS. 


36  37  38  39  40  41 

Figure  No.  Price. 

36.  Dividers,  German  Silver;  steel  joints,  turned  cheeks,  fine  finish, 

4-inch,  85  cents;  5-inch,  $1.10;  6-inch,  $1.25;  7-inch   $1  7i 

37.  Dividers,  German  Silver;  steel  joints,  turned  cheeks,  fine  finish, 

hair  spring,  4-inch,  $2.00;  5-inch,  $2.50;  6-inch   3  00 

38.  Dividers,  German  Silver;  fine  quality,  needle  point,  with  pen 

and  pencil  point,  3  inches   3  50 

39.  Dividers,  German  Silver;  fine  quality,  with  needle  point,  pen, 

lengthening  bar,  and  pencil  points,  6  inches    4  50 

40.  Dividers,  German  Silver;   5-inch,  fine  finish,  with  shield  for 

pocket   2  75 

41.  Dividers,  German  Silver;  5-inch,  three-legged   4  75 

42.  Proportional  Dividers,  German  Silver,  7^  inches  long,  divided 

for  lines   3  50 

43.  Proportional  Dividers,  German  Silver,  9  inches  long,  finely  di- 

vided for  lines  and  circles   13  25 

44.  Bisecting  Dividers,  German  Silver   1  50 

45.  Steel-Spacing  Dividers,  5  inches  long,  with  ivory  handle   3  25 

46.  do              do        3|       do             do      or  metal  handle,  1  75 

47.  Spring  Bow  Pen,  all  steel,  ivory  handle   2  25 

48.  Spring  Bow  Pencil,  ivory  handle  ,   2  25 

49.  Spring  Bow  Pen,  German  Silver   2  00 

50.  do                  do         with  pencil  point   3  30 


144 


DRAWING  INSTRUMENTS. 


42  44  45         46    47        51  52  66 

Figure  No.  Price. 

51.  Drawing  Pen,  German  Silver;  fine  finish,  hinge  to  pen,   $0  85 

52.  Drawing  Pen,  German  Silver*,  fine  finish,  hinge  to  pen,  and  pro- 

tracting pin   1  00 

53.  Drawing  Pen,  German  Silver;  fine  finish,  hinge  to  pen   1  00 

54.  do                 do           and  protracting  pin,  extra  fine, 
5^-inch   1  80 

55.  Drawing  Pen,  all  German  Silver,  for  red  ink   1  25 

66.  Double  Drawing  Pen,  or  Road  Pen,  fine  finish     3  50 


CASES  OF  FINE  GERMAN  SILVER  INSTRUMENTS, 

FOR  ENGINEERS,  ARCHITECTS,   AND  MACHINISTS. 

60.  Morocco  Box;  pair  of  5^-inch  Dividers,  with  Pen  and  Pencil 
Points,  Drawing  Pen,  Ivory  Scale,  6  inches  long,  same  as  in 


school-cases  of  instruments     4  50 

61.  Moroc^  Box;  pair  of  3-inch  Dividers,  with  Pen,  Pencil  and 
Needle-Points,  and  Lengthening  Bar,  Drawing  Pen.  No 
Scale  or  Protracor.    Per  set  •   5  50 


DRAWING  INSTRUMENTS. 


145 


Figure  No.  Price, 

62.  Morocco  Box;  pair  of  5^-inch  Dividers,  with  Pen  and  Pencil 

Points,  pair  of  5-inch  plain  Dividers,  Drawing  Pen,  Ivory 
Protractor  Scale,  6  inches  long,  per  set   $6  25 

63.  Same  as  No.  62,  with  addition  of  Needle  Points  and  Lengthening 

Bar  to  5^-inch  Dividers,  per  set   8  50 

64.  Morocco  Box,  rounded  corners,  for  carrying  in  the  pocket;  pair 

of  4|-inch  Dividers,  with  hinge  in  one  leg,  Needle  Points,  with 
Pen  and  Pencil  Points,  and  Lengthening  Bar,  Spring  Bow  Pen, 
Needle  Point,  pair  of  4-inch  plain  Dividers,  rounded  point. 
Drawing  Pen,  ivory  handle,  5-inch  Ivory  Inch  Rule,  divided 
into  eighths,  per  set   8  50 


65 


45  Morocco  Box;  pair  of  5|-inch  Dividers,  with  Pen  and  Pencil 
Points,  and  Lengthening  Bar,  pair  of  5-inch  plain  Dividers, 
pair  of  3-inch  Dividers,  with  Pen  and  Pencil  Points,  Drawing 
Pen,  German  Silver  Protractor,  German  Silver  Square,  Ivory 
Scale,  6  inches  long,  per  set   JO  80 

W.  Morocco  Box;  pair  of  5^-inch  Dividers,  with  Pen,  Pencil  and 
Needle  Points,  and  Lengthening  Bar,  pair  of  5-inch  plain  Di- 
viders, Spring  Bow  Pen,  Drawing  Pen,  Ivory  Protractor  Scale, 
6  inches  long,  per  set  *   10  80 


146 


DRAWING  IJNSTRUMENT8. 


67  73 

Figure  No.  Price. 

67.  Morocco  Box;  pair  of  5^-inch  Dividers,  with  Pen,  Pencil  and 

Needle  Points,  and  Lengthening  Bar,  pair  cf  5-inch  plain  Di- 
viders, pair  of  3-inch  Dividers,  with  Pen,  Pencil  and  Needle 
Point,  2  Drawing  Pens,  German  Silver  Square,  German  Silver 
Protractor,  Ivory  Scale,  6  inches  long,  per  set  $15  25 

68.  Same  instruments  as  in  No.  67,  in  polished  Walnut  Box,  per  set,  16  00 

69.  Same  iustfuments  as  No.  67,  omitting  Ivory  Scale,  German  Sil- 

ver Protractor  and  German  Silver  Square,  hut  in  polished 
Walnut  Box,  with  lock  and  tray   16  00 

70.  Polished  Walnut  Box;  same  instruments  as  No.  68,  with  the  ad- 

dition of  Spring  Bow  Pen  with  Needle  Point   18  00 

71.  Same  as  No.  70,  with  the  addition  of  5-inch  hair-spring  Dividers,  20  00 

72.  Same  as  No.  70,  set  in  a  tray,  and  the  box  much  larger,  with 

lock,  thus  affording  space  for  extra  instruments  or  colors,  Ac,  23  00 

73.  Polished  Walnut  Box,  with  lock  and  key,  instruments  set  in  a 

tray;  pair  of  5|-inch  Dividers,  with  Pen,  Pencil  and  Needle 
Points,  aTid  Lengthening  Bar,  pair  of  5-inch  plain  Dividers, 
pair  of  5-inch  hair-spring  Dividers,  pair  of  3-inch  Dividers, 
with  Pen,  Pencil,  and  Needle  Points,  pair  of  7^-inch  Propor- 
tional Dividers,  German  Silver  Square,  Spring  Bow  Pen,  with 
Needle  Point,  German  Silver  Protractor,  Ivory  Scale,  6  inches 

long  2  Drawing  Pens   40  00 

T4»  Polished  Walnut  Box;  instruments  same  as  No.  173,  with  addi- 
tion of  a  Railroad  or  Double  Drawing  Pen,  per  set   44  0§ 


PROTRACTORS  OF  HORN,  BRASS,  ETC.  147 


PROTRACTORS  OF  HORN,  BRASS,  GERMAN  SILVER, 
IVORI  AND  PAPER. 


Figure  No.  Price. 

80.  Horn  Protractors,  half  circle,  half  degrees,  5-inch  diameter^ 

$0.50;  6-inch,  $0.75;  7-inch,  $1.00 ;  8-inch    $1  25 

81.  Brass  Protractors,  half  circle,  whole  degrees,  4-inch   0  25 

do  do         half  degrees,  4-inch,  $0.50;   5-inch,  $0.75; 

6  inch   1  00 

82.  German  Silver  Protractor,  4  inches  diameter,  ^  circle,  whole  deg.  0  75 

do  do        half  degrees,  5-inch,  $1.25;  6-inch, 

$1.50;  7-inch   1  75 

83.  German  Silver  Protractors,  with  beveled  edges,  5-inch,  $1.75; 

6-inch,  $2.50;  7-inch   3  25 

84.  Paper  Protractor,  whole  circle,  ^  degrees,  12-inch  thin  paper...  0  30 

do        do           do       do     ^  degrees,  12  inch  Bristol  board.  0  40 

do        do         half  circle,  ^  degrees,  5-inch  card  board   0  25 

do        do              do         whole  degrees,  4-inch  card  board.  0  20 

85 


85.  Ivory  Protractor,  6  inches  long,  1|  inches  wide,  whole  degrees, 

with  6  scales  of  equal  parts,  4  scales  of  feet  and  inches,  2  scales 

of  chords  and  diagonal  scale  «   1  50 

86.  Ivory  Protractor,  6  inches  long,  1|  inches  wide,  whole  degrees, 

with  6  scales  of  equal  parts,  8  scales  of  feet  and  inches,  2  scales 

of  chords  and  diagonal  scale     2  50 

87.  Ivory  Protractor,  6  inches  long,  2  inches  wide,  whole  degrees, 

with  8  scales  of  equal  parts,  10  scales  of  feet  and  inches,  2 
scales  of  chords,  diagonal  scale  and  line  of  40  on  lower  edge..    3  30 

88.  Ivory  Protractor,  same  as  No.  87,  but  in  half  degrees  , ,.    4  50 

874.    do        do         6  inches  long,  2^  inches  wide,  half  degrees, 

with  10  scales  of  equal  parts,  12  scales  of  feet  and  inches,  2 
scales  of  chords,  diagonal  scale,  and  line  of  40  on  lower  edge,    %  75 


148 


IVORY  AND  BOXWOOD  SCALES. 


Figure  No.  Price. 

89.  lyory  Protractor,  6  inches  long,  2^  inches  wide,  with  8  scales  of 
equal  parts,  12  scales  of  feet  and  inches,  3  scales  of  chords, 
lines  of  sines,  tangents,  secante,  hours,  &o,  &c.,  and  line  of  40 
on  lower  edge   $7  75 

yO.  Ivory  Protractor,  8  inches  long,  2  inches  wide,  half  degrees,  with 
6  scales  of  equal  parts,  8  scales  of  feet  and  inches,  2  scales  of 
chords,  diagonal  scale  and  line  of  40  on  lower  edge   5  75 

91.  Ivory  Protractor,  12  inches  long,  2^  inches  wide,  half  degrees, 
with  10  scales  of  equal  parts,  12  scales  of  feet  and  inches,  2 
scales  of  chords,  diagonal  scale  and  line  of  40  on  lower  edge. . .  13  50 


lYORY  AND  BOXWOOD  SCALES. 
d2.  Boxwood  Protractor,  6  inches  long,  Ij  inches  wide,  whole  de- 
grees, with  6  scales  of  equal  parts,  4  scales  of  feet  and  inches, 
2  scales  of  chords^  and  diagonal  scale   0  75 

IVORY  SCALES. 


95 

93.  Ivory  Sector,  6  inches,  opens  to  12  inches   2  25 

94.  Ivory  Scale,  6  inches  long,  same  as  in  school  cases  of  instruments,    0  80 

95.  Ivory  Chain  Scales,  12  inches  long,  graduated  on  two  edges  with 

either  10  and  10  parts,  or  10  and  20,  or  20  and  40,  or  30  and 

60,  or  40  and  60,  or  50  and  60,  each   3  50 

do       do       do       do       with  40  and  80,  or  50  and  100,  each.    6  00 

96.  Ivory  Architects'  Scales,  12  inches  long,  each.   3  50 

do  do  do  with  diagonal  scale  on 

one  side,  each   3  50 

do                   do                   do          with  16  different  gradu- 
ations all  brought  to  the  edges,  each   3  50 

BOXWOOD  SCALES. 

97.  Boxwood  Scale,  6  inches  long,  same  as  in  school  cases  of  instru- 

ments   0  30 

98.  Boxwood  Scale,  12  inches  long,  for  Architects   1  25 

©9.  do  12  do       with  16  different  graduations,  all 

brought  to  the  edges   1  25 


PAPER  SCALES,  STEEL  RULES,  ETC.  149 


Figure  Tfo.  Price. 

100.  Boxwood  Scale,  12  inches  long,  for  Architects,  with  diagonal 

scale  on  one  side  »   $1  25 

101.  Triangular  Scale  of  Boxwood,  24  in.  long,  graduated  10,  20,  30, 

40,  50  and  60  to  the  inch   5  00 

102.  do  do  do  do  12  inch,  2  00 
L02^.        do             do             do             do  6  inch,    1  50 


.  102 

t03.  Triangular  Scale  of  Boxwood,  24  in.  long,  graduated  3    3    |,  |, 

oZ  16 

I,     I,  1,       3  and  16ths  to  the  foot   5  00 

104.  do  do  do  do  12  inches  long,  2  00 

105.  do  do  do  do  6        do  1  60 

106.  Boxwood  Gunter  Scales,  12  inches  long   0  65 

107.  Satin  Wood    do     do       24       do    1  00 


PAPER  SCALES,  STEEL  RULES,  &c. 
PAPER  SCALES. 

108.  Paper  Scale,  on  card  paper,  1^  inches  wide,  12  inches  long;  one 

edge  inches  and  lOths,  and  the  other  feet  and  lOOths   0  10 

109.  Paper  Scale,  12  in.,  one  edge  20  parts  to  the  inch,  the  other  40,    0  10 

110.  Paper  Scale,  12  inches,  one  edge  inches  and  sixteenths;  the 

other  inches  and  forty-eighths   0  10 

111.  Paper  Scales,  on  card  paper,  19  inches  long,  for  architects  and 

engineers,  in  sets  of  6  scales,  per  set   1  00 

112.  Series  A  contains  6  scales,  one  each,  divided  to  ^,  ^,  ^,  1,  1^  and 

3  inches  to  the  foot,  for  architects   1  00 

113.  Series  B  contains  6  scales,  one  each,  divided  to  3-32,  ^,  3-16, 

5-16,  I  and  |  inch  to  the  foot,  for  architects   1  00 

114.  Series  C  contains  6  scales,  one  each,  divided  to  10,  20,  30,  40, 

50  and  60  parts  to  the  inch,  for  engineers   1  00 

Single  Scale  of  any  of  the  above  series,  A,  B,  C — each  scale  ...    0  20 

115.  Paper  Scales,  19  inches,  divided  either  to  |,  Ig,  1^  or  1|  inches 

to  the  foot,  each   0  20 

The  advantages  of  these  scales  are — they  expand  and  con- 
tract nearly  the  same  as  drawing-paper,  do  not  soil  the 
work,  and  distances  can  be  set  off  from  them  without  the 
use  of  the  dividers. 


150  STEEL  TOOLS  FOR  MACHINISTS,  ETC. 


STANDARD  STEEL  RULES  FOR  MACHINISTS. 

Figure  No.  Price. 

116.  24  inch  steel  rule,  divided  into  8ths,  lOtlis,  12ths,  14ths,  16tlis, 

20ths,  24ths,  28ths,  32ds,  48ths,  60ths,  64ths,  and  lOOths  of  an 

inch   $4  00 

117.  12  inches                    do                   do                   do  2  00 

118.  9  inches                    do                   do                   do  1  50 

119.  Cinches                     do                   do                   do  1  00 

120.  4  inches                    do                   do                   do  0  75 

121.  3  inches                    do                   do                   do  0  50 

SHRINK  RULES  FOR  PATTERN  MAKERS. 

122.  24^  inch  single  shrink,  full,  divided,  Steel   4  50 

128.  24^       do             do          do            Boxwood   3  00 

124.  24^  inch  double  shrink,  8ths  and  16ths,  Steel   4  50 

125.  24^          do             do             do          Boxwood   3  00 

STANDARD  SCALES  STEEL. 

126.  36  inch  Steel  or  Standard  Yard,  full,  divided   8  00 

127.  36  inch  Steel  Standard  Yard,  |  in.  square,  divided  to  feet  only,  2  00 

128.  French  Standard  Metre,  divided  on  3  edges  to  millimetres,  and 

one  edge  to  5ths  of  millimetres   10  00 

129.  Centre  Gauge  for  lathes,  also  for  screw  tools   0  50 

130.  Horse-shoe  Magnets,  steel,  2-inch,  $0.15;  2i-inch,  $0.20;  3- 

inoh,  $0.40;  4-inch,  $0.50;  5-inch,  $0.70;  6-inch   1  01? 


STEEL  SQUARES  FOR  MACHINISTS. 


'I'M' 
3 

2 

131 

131   Steel  Squares,  with  3-inch  blade,  $2.50 ;  4-inch,  $3.00;  6-incb, 

$3.50;  9-inch,  $4.00;  12-inch  ,   6  00 


TRIANGLES,  SQUARES,  ETC.  151 

Figure  No.  Price. 

132.  Hardened  Cast-steel  Try  Squares,  for  machinists,  15-inch,  $15 
12-inch,  112;  9-inch,  $9;  6-inch,  $6;  4i  inch,  $4.50 ;  3-inch 
$3.50;  i^-inch   $2  50 


.  133 

183.  Steel  Bevel  Protractor,  with  sliding  arm,  divided  to  degrees, 

for  machinists ;  with  6-inch  arm,  $6 ;  with  10-inch  arm   6  51 


TRIANGLES,  SQUARES,  &c. 


139 


152 


TRIANGLES,  SQUARES,  ETC. 


Figure  No.  Price. 

134.  Hardened  Cast-steel  Pocket  Vernier  Calliper;  vernier  to  lOOOths 

of  inches,  one  edge  to  millimetres,  $6;  in  morocco  case  ......  $7  00 

135.  Improved  Vernier  Calliper,  vernier  reads  to  lOOOths  of  inches 

inside  and  outside  Callipers,  and  points  to  transfer  the  dis- 
tance, with  dividers;  in  morocco  case;  6-inch,  $18;  12-inch, 
$25;  24-inch....  ,   30  00 

136.  Calliper  Squares,  divided  to  lOOths  and-64ths  of  inches;  2-inch, 

$3.50;  3-inch   4  50 

137.  Steel  Straight  Edge,  48  inches  long,  $9  ;  86-inch,  $6 ;  SO-inch, 

$5;  24-inch   3  00 

188.  Polished  Rosewood  Straight  Edge,  20-inch,  $0.60;  80-in.,  $0.75; 

40-inch,  Sl.CO  ;  60-inch,  $1.50  ;  60-inch,  $2.60  ;  72-inch   4  60 

139.  Ames'  Patent  Universal  Square,  blade  6  inches  long,  $3;  8-in. 

$4;  10-inch,  $5;  12-inch    6  00 

140.  Pearwood  Triangles,  30,  60  and  90  degrees,  and  45,  45  and  90 

degrees;  5  to  7-inch,  $0.25;  7  to  10-inch,  $0.35;  12-inch  ....  0  45 
341.  Rosewood  or  Beachwood  Triangle,  framed,  degrees  as  No.  140, 

plain  finish;  6  to  10-inch,  $0.50;  12  to  15-inch   1  10 

142.  Rosewood  or  Beachwood  Triangle,  polished,  6  to  9-iii.,  $0.60 ;  12 

to  15-inch   1  25 

143.  Hard  Rubber  Triangle,  6-inch,  $0.75;  7-inch,  $0.85;  8-iii.,  $1.10; 

9-inch   1  25 

344.  Ger.  Silv.  Triangle,  30,  60  and  90  deg.  perpendicular,  6  to  7  in.    2  50 

145.  do  do  do  do  do  9  to  10  in.    4  00 

146.  do  do       45,  45  and  90  deg.     do  4  to  5  in.    2  25 

147.  do         do  do         do         do  6  to  7  in.    4  00 

148.  do     Squares,  perpendicular,  6  to  7  inches   1  10 

CURVES,  T  SQUARES,  ETC.,  ETC. 

149.  TVhitewood  Irregular  Curves,  5  to  9  inches  long,  various  pat- 

terns, each  $0.35 ;  10  to  12-inch,  $0.75;  13  to  18-inch,  each. . .    1  10 

150.  T  Square,  Pearwood  or  Beech,  fixed  head,  blade  15  inches  long, 

each  $0.50;  20-inch,  $0.75;  30-inch,  $0.85;  40-inch,  $1;  50- 
inch    1  75 

151.  T  Square,  Rosewood  or  Beach  (fig.  150),  polished,  30-inch, 

$1.75;  40-inch   2  50 

152.  T  Square,  Pearwood  or  Beech,  single  head  to  turn;  head  takes 

off  and  blade  can  be  used  as  a  rule;  20  inch,  $1  25;  30-inch, 
$1.50;  40-inch,  $1.75;  50-inch    2  00 

163.  T  Square,  Pearwood  or  Beech,  double  head,  24-inch,  $1.75;  30- 
inch.  $2.25;  40-inch   2  75 

154.  T  Square,  Roeewocd,  polished  (fig.  153),  30-inch,  $2.75;  42-in.    4  00 


PARALLEL  RULES,  ETC. 


153 


PARALLEL  RULES,  &c. 
Figure  No.  Price, 
155.  Parallel  Rulers,  Ebony,  brass  mounted,  6  inches  long,  each, 
$0.35;  9-inch,  $0.75;  12-inch,  $1;  15-inch,  $1.25;  18-inch, 
$1.50;  24-inch  $3  00 

155  159 

153.  Parallel  Rulers,  German  Silver,  mounted,  12-inch   1  75 

157.       do        do      all  German  Silver,  on  rollers,  15-inoh,  $10; 

18-inch   12  00 

153.  Parallel  Rulers,  all  Brass,  on  rollers,  9-inoh,  $6.25;  12-inch, 

$8.25;  15-inch   10  50 

159.  Parallel  Rulers,  Ebony,  on  rollers,  12-inch,  $4.25 ;  15-inch.  $5; 

18-inch    6  26 


154  IVORY  AND  BOXWOOD  RULES. 


Figure  No.  Price. 

160.  Parallel  Rulers,  Ebony,  ivory  graduated  edges,  12-incli,  $6.50; 

15-inch,  $8;  18-inch   $10  00 

162     161  166  165 

161.  Engineers'  Tacks,,  thick  heads,  brass,  per  doz....   0  30 

162.  do  do      thin  heads       do       do    0  40 

163.  do  do  do  German  Silver,  per  doz   0  75 

164.  do  do  do    Ger.  Sil.  large  &  extra  fine,  per  doz.  1  50 

165.  do  no      right  angle  brass,  3  points,  per  doz   0  75 


166.  Horn  Centres,  to  prevent  the  dividers  from  marking  the  paper.    0  25 
IVORY  AND  BOXWOOD  RULES. 


167 


167  Combination  Rule,  1  foot,  2  fold,  boxwood.  This  is  the  most 
convenient  and  useful  pocket-rule  ever  made;  it  combines  iu 
itself  a  Carpenter's  Rule,  Spirit  Level,  Square,  Plumb,  Bevel, 


SPIRIT  LEVELS  AND  POCKET  COMPASSES.  155 


Figure  No.  Price. 
Indicatofj  Brao3,  Scale,  Draughting  Scale  of  equal  parts,  T 
Square,  Protractor,  Right  angle  Triangle,  and  with  a  straight 
edge  can  be  used  as  a  Parallel  Ruler,  all  the  parts  of  which, 
in  their  separate  applications,  are  perfectly  reliable....  $3  50 

168.  Combination  Rule,  1  foot,  2  fold;  ivory,  same  as  above   8  00 

An  explanation  and  directions  for  use  accompanies  each  of  the 
Combination  Rules. 

POCKET  RULES. 

169.  One  foot,  4  fold,  boxwood,  each    0  35 

170.  do         do  do        brass  edges   1  00 

J71.       do         do      ivory,  brass  mounted   1  00 

172.  do         do      German  Silver,  mounted   1  50 

173.  do         do  do  do        graduated    in  lOths 

and  lOOths,  for  engineers   1  50 

174.  do        do  do         edges   2  75 

175.  Two  feet,  4  fold,  boxwood....*   0  50 

170.       do  do        do       brass  edges   1  25 

177.  do  do     ivory,  German  Silver  bound,  with  8th,  10th 

and  16th  inches,  and  ^,  -i,  |  and  1  inch  drafting  scales   6  50 

178.  do  do  do  German  Silver  edges..    7  50 

179.  Two  feet,  6  fold  rules,  boxwood,  graduated,  8th,  10th,  and  16th 

inches   1  25 

180.  do  do  ivory,  graduated,  8th,  10th,  10th  and 

16th  inches   6  50 


SPIRIT  LEVELS  AND  POCKET  COMPASSES. 


185 

185.  Locke's  Hand  Level,  made  of  German  Silver   12  00 

186.  do          do          do        brass   10  00 

187.  Levels,  mounted  in  brass,  for  mechanical  purpose^^,  3  to  12  in. 

long,  per  inch   0  25 

188   Level  Bulbs,  unmounted,  2  to  4  inches,  25c ;  4  to  6  inches   0  35 


156 


POCKET  COMPASSES. 


187 

Figure  No.  Price- 
189.  Spirit  Levels,  for  millwrights,  mahogany  stock,  with  3  ground 

level  vials  set  in  brass,  all  adjustable,  24  and  30-inch  $6  00 

ISO.  Spirit  Levels,  for  millwrights,  with  2  ground  level  vials,  ad- 
justable, 24  and  30-inch   4  50 

191.  Spirit  Levels,  with  unground  level  vials,  of  good  quality;  3 

levels,  $4;  2  levels   3  00 

192.  Brass  Plumb  Bobs,  steel-point  sarew  heads;  3-oz.  $1;  6-oz. 

$1.50;  10-oz.  $1.75;  14-oz.  $2.25;  20-oz.  $2.75;  24-oz.  $3; 
32-oz   3  50 


POCKET  COMPASSES. 


195  200  198 

195.  Mahogany  Case,  with  stop  to  needle,  1^  inches  square,  $1.75; 

2-inch,  $2;  2^  inch,  $2.50 ;  3-inch   3  00 

196.  Brass,  round,  with  cover,  1^  inches  diameter,  stop  to  needle  ...    1  50 

197.  do  do  do  do  do  and 

agate  centre  to  needle  ,   2  25 

198.  do  watch  pattern,  stop,  agate  centre,  1^  in.,  $1.50; 

2-inch    2  25 

199.  do  watch  pattern,  stop,  agate  centre,  1^-inch,  with 

hinged  cover    3  00 

200.  do  Gilt  Charm  Compasses,  to  hang  to  watch-guard..    0  25 

201.  Solid  Gold  Charm  Compasses  do  do         ..    3  00 

Also;  a  variety  of  cheap  Pocket  Compasses,  in  wood  and  brass, 
from  25  to  75  cents  each. 


MICROSCOPES,  ETC. 


157 


MICROSCOPES,  &c. 
SIMPLE  MICROSCOPES  TO  FOLD  IN  CASES. 


210          212               213                  2U                216  217 
Figure  No.  Price. 
210.  Hard  Rubber  case  and  frame,  round  form,  1  double  convex  lens, 
I  inch  diameter,  $.50;  1-inch,  $0.75;  1^-inch,  $1;  l^-inch, 
$1.25;  l|-inch,  $1.50;  2-inch   $2  25 


211.  Hard  Rubber  case  and  frame,  round  form,  2  double  convex 

lenses,  }-inch,  $0.75;  1-inch,  $1.25;  1^-inch,  $2;  11-inch...  2  50 

212.  Hard  Rubber  case  and  frame,  bellows  form,  |- in.  $0.75;  1-in.  1  00 

213.  do  do  do     2  lenses,  |-in.  $1 ;  1-in.  125 

214.  do  do  do     3  do  |-in.  $1.50 ;  1-in.  1  75 

215.  Microscope  on  three  legs,  with  screw  adjustment  for  focus   1  00 

216.  Linen  Provers,  or  Microscope  for  counting  the  threads  in  linen 


fabrics   *   0  75 

217.  Stanhope  lens,  in  German  Silver  frame  ,   1  50 

218.  Coddington  lens,  brass  frame   2  00 

219.  do  silver  frame   2  50 

220.  do  do        with  cover   3  50 


221.  do  do        large  size,  with  cover    5  50 

BEADING  AND  PICTURE  LENSES. 


226  229 


225.  Reading  Glass,  hard  rubber  frame,  double  convex  lens,  ^-inch 
diameter,  $0.35;  l|-inch,  $0.85;  2-iuch,  $1.50;  2i-inch,  $3; 
3-inch   3  75 


158 


MARINE,  OR  HELD  GLASSES . 


Figure  No.  Price, 
226.  Reading  Glass,  oxidized  metal  frame,  double  convex  lens,  2- 
'   inch,  $1;  2^-inch,  $1.50;  3-inch,  $2;  3^-inch,  $2.50 ;  4-inch, 
$3.25;  4|-inch   $5  00 


227.  Reading  Glass,  oxidized  metal  frame,  two  plano-convex  lenses, 

2i  inches  diameter,  $2.25;  3-inch,  $3;  3^-inch,  $4.25 ;  4-in..    5  00 

228.  Reading  Glass,  gilt  metal  frame,  ivory  handle,  one  double  con- 

vex lens,  2-inch,  $2.25;  2^-inch,  $2.75;  3-inch,  $3.75;  4-in., 
$4.75;  4^-inch   6  50 

229.  Reading  Glass,  black  metal  frame,  wood  handle,  double  convex 

lens,  3  inches  long  by  1^  inches  wide,  $1  50;  3|xl|  inches,  $2; 

4x2  inches   2  50 

230.  Picture  Glasses,  rosewood  frame  and  handle,  double  convex 

lens,  5  inches  diameter,  $5 ;  6-inch  7  50 


ACHROMATIC  OPERA  GLASSES. 
Diameter  of  object-glasses  given  in  lines  12  to  1  inch. 

235.  Six  lens,  metal  body,  japaned,  black,  13  lines,  $5.25;  15  lines, 

$5.75;  17  lines,  $7;  19  lines,  $8.50;  21  lines,  $9.50;  24  lines,  12  00 

236.  Six  lens,  metal  body,  covered  with  black  imitation  Turkey  mo- 

rocco, bars  connecting  the  two  bodies  curved;  13  lines,  $8.25; 

15  lines,  $10.50;  17  lines,  $11;  19  lines,  $12.75;  21  lines   14  76 

237.  Twelve  lens,  metal  body,  covered  with  imitation  Turkey  mo- 

rocco, superior  quality;  13  lines,  $13;  15  lines,  $14;  17  lines. 


$16.50;  19  lines,  $18;  21  lines   19  50 

238.  Twelve  lens,  metal  body,  covered  with  black  Turkey  morocco, 
superior  quality;  13  lines,  $15;  15  lines,  $16.50;  17  lines, 
$18.50;  19  lines,  $21;  21  lines  ,  24  Oft 


Also,  a  large  variety  mounted  in  pearl,  enamel,  and  oxidized 
metal. 

MARINE,  OR  FIELD  GLASSES. 

239,  Six  lens  Achromatic  Field  Glass,  metal  body,  covered  with  Tur- 
key morocco,  sun  shade  to  extend  over  the  object-glasses,  and 


soft  leather  case,  with  strap. 

Body  3|  inches  long;  object-glasses  16  lines  in  diameter  .....  9  00 

do    4^         do  do  17  do    10  60 

do    4-1         do  do  19  do    11  25 

do    4|         do  do  21  do    12  00 

do    5|          do  do  24  do    14  00 

do    Ql         do  do  26  do    16  00 


ACHROMATIC   TELESCOPES.  159 

Figure  No.  Price. 

240.  U.  S.  Army  Signal  Service  six  lens  Achromatic  Field  Glass, 
metal  body,  covered  with  Turkey  morocco,  sun  shade  to  ex- 
tend over  the  object-glasses,  and  heavy  leather  case,  with 
strap;  very  superior. 

Body,  5|  inches  long;  object-glasses  21  lines  in  diameter  $17  00 

do    5J  do  do  24  do    20  00 

do    6^         do  do  26  do    22  00 


ACHROMATIC  TELESCOPES. 
251 

241.  Telescope,  wood  body,  3  draws,  15  inches  drawn  out,  6  inches 

shut,  object-glass  1  inch  in  diameter,  power  15  times   $3  50 

242.  Telescope,  wood  body,  3  draws,  16  inches  drawn  out,  6  inches 

shut,  object-glass  \\  inches  in  diameter,  power  20  times   4  26 

243.  Telescope,  wood  body,  3  draws,  23  inches  drawn  out,  8  inches 

shut,  object-glass  1§  inches  in  diameter,  power  25  times   7  00 

244.  Telescope,  wood  body,  3  draws,  30  inches  drawn  out,  10  inches 

shut,  object-glass  1|  inches  in  diameter,  power  30  times   9  00 

245.  Telescope,  wood  body,  4  draws,  37  inches  drawn  out,  11  inches 

shut,  object-glass  1^  inches  in  diameter;  superior  glass;  power 

35  times   17  00 

246.  Telescope,  wood  body,  4  draws,  42  inches  drawn  out,  11^  inches 

shutj  object-glas  2^  inches  in  diameter,  power  40  times   30  00 

247.  Telescope,  wood  body,  4  draws,  48  inches  drawn  out,  13j  inches 

shut,  object-glass  2|  inches  in  diameter,  power  45  times  41  00 

248.  Telescope,  wood  body,  5  draws,  28  inches  drawn  out,  7|  inches 

shut,  object-glass  1|  in.  in  diameter;  about  the  same  power 

as  No.  245,  but  more  portable;  power  35  times     12  00 

249.  Telescope,  wood  body,  6  draws,  17  inches  drawn  out,  4|  inches 

shut,  object-glass  1^  inches  in  diameter,  power  20  times   8  00 

250.  Telescope,  wood  body,  6  draws,  16  inches  drawn  out,  4^  inches 

shut,  object-glass  |  inch  in  diameter;  very  portable;  power 

15  times   7  00 

251.  Telescope,  brass  body,  covered  with  cord  or  leather;  shade  to 

keep  off  the  sun  and  rain;  1  draw,  36  inches  drawn  out,  20  in. 
shut,  power  25  times   15  00 

252.  Same  as  above,  but  with  2  or  3  draws;  15  inches  shut   15  00 


160  ACHROMATIC  TELESCOPES 


253 

Figure  No.  Price. 

253.  Tourist's  Achromatic  Spy-glass,  with  brass  body,  covered  with 
Turkey  morocco;  3  draws,  17  inches  drawn  out,  6  inches  shut, 
object-glass  1^  inches  diameter;  sun  shade  to  slip  beyond  the 
object-glass;  heavy  leather  caps  to  cover  both  the  eye-glass 
and  object-glass;  strong  leather  strap  to  sling  over  the  shoul- 


der: power  20  times  $12  00 

264.  Same  as  No.  253,  but  is  21  inches  drawn  out,  7  inches  shut,  ob- 
ject-glass 1|  inches  diameter;  power  25  times   15  50 

255.  Same  as  No.  253,  but  is  24  inches  drawn  out,  9  inches  shut,  ob- 

ject-glass 1|  inches  diameter,  power  30  times   21  00 

256.  Same  as  No.  253,  but  has  4  draws,  and  is  36  inches  drawn  out, 

10  inches  shut,  object-glass  IJ  in.  diameter,  power  35  times..  30  00 

257.  Brass  Clamp  with  gimlet  screw,  to  fasten  a  Spy -glass  to  a  post 

or  tree  •   3  50 


DRAWING  AND  TRACING  PAPERS,  ETC.  161 


Drawing  IPaper^  Colors,  &c. 


In  filling  orders  for  Instruments  from  different  parts  of  the 
country,  we  have  frequently  been  called  upon  to  furnish,  in 
addition,  the  various  materials  for  the  office  work  of  the  Sur- 
veyor and  Engineer,  as  Drawing  Paper,  Colors,  Text  Books, 
&c.  We  have  therefore  supplied  ourselves  with  an  assortment 
of  these  goods,  and  shall  hereafter  be  able  to  furnish  them  on 
as  favorable  terms  as  any  other  dealer  in  the  Union. 

WHATMAN'S  TURKEY  MILL  DRAWING  PAPERS. 
Demy   20x15  inches,  per  sheet,  7  els.;  per  quire....  $1  60 


do 

do 

9 

do 

, . . .    2  00 

do 

do 

11 

do 

. . . .    2  50 

27x19 

do 

do 

13 

do 

....    3  00 

80x21 

do 

do 

20 

do 

...    4  50 

28x22 

do 

do 

20 

do 

, . . .    4  50 

do 

do 

30 

do 

...    6  00 

.  35x26 

do 

do 

30 

do 

...    6  00 

,  .  40x26 

do 

do 

35 

do 

...    8  00 

52x31 

do 

do  $ 

1  25 

do 

...  25  00 

DRAWING  PAPER  IN  ROLLS. 

ANY  LENGTH. 

White,  Extra  Thick,  40  inches  wide,  per  yard    

do  do  64        do  do   

Buff  Tint,  Bleached  Manilla,  exceedingly  strong  and  tough,  for 
working  plans,  45  inches  wide,  extra  thick,  per  yard  

DRAWING  PAPER  ON  MUSLIN. 

In  Rolls  8  yards  long  and  40  inches  wide,  per  yard   1  50 

do     8       do       do     54        do  do    2  00 

VELLUM,  OR  TRACING  CLOTH. 
Sagar's  Patent. 

18  inches  wide,  in  rolls  of  24  yards,  per  yard,  $0.50;  per  piece    9  00 

36        do  do  do         do  1.00;      do    18  00 


162        DRAWING  AND  TRACING  PAPERS,  ETC. 


FRENCH  TRACING  PAPER. 
Fine  quality,  very  clear  and  strong* 

In  Sheets.    Royal,  19  by  25  inches,  per  quire   $2  05 

do          Super-royal,  21  by  26  inches,  per  quire  -.   2  56 

do          Double  Elephant,  28  by  40  inches,  per  quire   4  2h 

In  Rolls  11  yards  long  and  43  inches  wide,  per  yard,  $0.35;  per  roll,  2  06 

do     22          do           43          do          do           0.35;       do  4  Od 

PROFILE  PAPER. 

Plat«  A,  42x15  in.,  horizontal  ruling,  4,  vertical,  20  to  in.,  per  sheet,  0  40 

Plate  B,  42x13^             do                4,     do       30    do          do  0  40 

Plate  C,  42x15              do                6,     do       25    do          do  0  40 

Continuous  Profile  Paper  Plates,  A  and  B,  per  yard   0  30 

Muslin  Backed  Continuous  Profile  Paper,  A  and  B,  per  yard   0  76 

CROSS  SECTION  PAPERS. 
Trautwine's  Cross  Section  and  Diagram,  10  feet  to  inch,  for  embank- 
ments of  14  and  24  feet,  roadway,  and  for  excavations  of  18 

and  28  feet,  ruling  19.^x12  inches,  per  sheet   0  25 

Cross  Section,  ruling  22x16  inches,  8  feet  to  inch,  per  sheet ....... ,  0  25 

Cross  Section,  ruling  13^x16  inches,  10  feet  to  inch,     do    0  25 

Ruled  and  Section,  14x17  inches,  4  feet  to  inch,          do    0  01. 

LYONS'  TABLES. 


A  set  of  Tables  for  finding  at  a  glance,  the  true  cubical  contents  of  Exca- 
vation and  Embankments  for  all  Bases  and  for  every  variety  of  GrouM«k 
and  Side  Slopes;  by  M.  E.  Lyons,  C.  E. 


Bheet  No  1.  General  Table  for  all  Bases  and  all  Slopes. 


do 

2. 

For  Side  Hill  Cuts  and  Fills. 

do 

3. 

Base 

do 

4. 

do 

14 

do 

5. 

do 

15 

do 

6. 

do 

15 

do 

7. 

do 

15 

do 

8. 

do 

16 

do 

9. 

do 

16 

do 

10. 

do 

18 

do 

11. 

do 

18 

do 

12. 

do 

18 

do   

  1    to  1 

do 

13. 

do 

18 

do 

14. 

do 

20 

do 

15. 

do 

24 

do 

16. 

do 

24 

do 

17 

do 

25 

1.9 

do 

26 

DRAWING  AND  TRACING  PAPERS,  ETC. 


163 


Sheet  No.  19.  Base  28  feet  Slopes   ^  to  1 

do      20.    do    30       do   1   to  1 

do      21.    do    30      do    1^  to  l 

do      22.    do    30       do   If  to  1 

do      23.    do    32       do    1   to  1 

do      24.    do    32       do    1^  to  : 


The  Tables  are  printed  in  clear,  bold  type  on  tinted  paper,  sheets 
25x16  inches.  They  may  be  used  by  candle-light  without  injuring 
the  eye-sight.  Each  sheet  is  complete  in  itself,  and  embraces  all 
that  is  wanted  in  connection  with  the  Base  or  Slope  designated, 


whether  on  level  or  side-hill  cross  section. 

Per  sheet,  $0.25;  bound  in  one  volume   <8  50 

FIELD  BOOKS. 

Level  Books,  each   0  75 

Transit  Book,  do   0  75 

Record            do    0  90 


Lithographic  or  Steel  Plate  engraved.  Letter  Headings,  Papers, 
Envelopes,  Ink,  Pens,  and  every  description  of  office  Stationery 
furnished  to  order,  of  the  best  quality. 

PAPER  PROTRACTOR— SHEETS  AND  BOARDS. 
Whole  Circle  Protractors',  12  in.  diam.  ^  degrees,  thin  paper,  each,    0  30 
do  do  do  do        Bristol  boards  do     0  40 

INK  SLABS,  SAUCERS  AND  WATER  COLORS. 


INK  SLABS 

For  India  Ink  and  Colors;  containing  3  holes  or  cups  and  1  slanting 


division. 

Measuring  2|  by  1|  inches,  each   0  20 

do       3   by  2  do   0  35 

do       4  by  2|        do   0  40 

CABINET  NESTS. 
Porcelain  Saucers  in  Nests;  fitted  on  each  other. 

Containing  6  Saucers,  2^  inches  in  diameter,  per  nest   1  00 

do       a     do      2|  do  do    1  2d 


164       DRAWING  AND  TRACING  PENCILS,  ETC. 


WINSOR  &  NEWTON'S  WATER  COLORS. 
In  Half  and  Whole  Cakes, 
Whole  cakes,  35  cents ;  half  cakes,  20  cents. 

Antwerp  Blue,  Gamboge,  Payne's  Grey, 

Bi^tre,  Hooker's  Green,  No.  1,  Prussian  Blue, 

Blue  Black,  Hooker's  Green,  No.  2,  Prussian  Green, 

British  Ink,  In.ligo,  Raw  Sienna, 

Brown  Ochre,  Indian  Red,  Raw  Umber, 

Brown  Pink,  Italian  Pink,  Red  Lead, 

Burnt  Roman  Ochre,        Ivory  Black,  Roman  Ochre, 

Burnt  Sienna,  King's  Yellow,  Sap  Green, 

Burnt  Umber,  Lamp  Black,  Terre  Verte, 

Chrome  Yellow,  Light  Red,  Vandyke  Brown, 

Deep  Chrome,  Naples  Yellow,  Venetian  Red, 

Dragon's  Blood,  Neutral  Tint,  Vermilion, 

Emerald  Green,  Olive  Green,  Yellow  Lake, 

Flake  White,  Orange  Chrome,  Yellow  Ochre. 

Whole  Cakes,  65  cents ;  half  cakes,  35  cents. 


Brown  Madder, 
Chinese  White, 
Constant  White, 
Crimson  Lake, 
Indian  Yellow, 

Whole  cakes,  90  cents 
Cobalt  Blue, 

Whole  cakes,  $1.25 
Aureolin, 
French  Blue, 


Mars  Yellow, 
Neutral  Orange, 
Purple  Lake, 
Roman  Sepia, 
Ruben's  Madder, 

half  cakes,  50  cents. 
I  Orange  Vermillion, 
half  cakes,  65  cents. 
Green  Oxide  of  Chrome^ 
Intense  Blue, 
Lemon  Yellow,  ; 


Whole  cakes,  $2.00;  half  cakes,  3^1.00. 


Burnt  Carmine, 
Cadmium  Yellow, 
Cadmium  Orange, 
Carmine 


Gallstone, 
Pure  Scarlet, 
Madder  Carmine, 
Mars  Orange, 


Scarlet  Lake, 
Scarlet  VermillUn, 
Sepia 

Warm  »:>ep.a.. 


VidltfC  Carmine* 


Pink  Madder, 
Rose  Madder. 


Purple  Madder, 
Smalt, 

Ultramarine  Ash. 


OSBORNE'S  WATER  COLORS. 
Mahogany  and  Rosewood  Chests,  with  Lock,  Drawer,  Paint  Stone,  Watei 
Glass,  India  Ink,  Brushes,  and  12  colors.. $10  00 


Mahogany,  etc.  do  do  do  18    do    11  50 

Mahogany,  etc.  do  do  do  24    do    14  00 

Mahogany,  etc.  do  do  do  24  half  cakes,  10  10 

INDIA  INK. 

India  Rubber,  best  quality,  each    ...  6  to  50  cents. 

India  Ink,  best  quality,  20c,  25c,  35c,  50c,  75c  and  .    $1  00 

Mouth  Glue,  slips   4  cents. 


DRAWING  AND  TRACING  PENCILS,  ETC.  165 


MAPPING  AND  CROW-QUILL  PENS. 

Gillott's,  on  cards  per  dozen   $0  85 

Gillott's  Lithographic  Crow-Quill,  on  cards                  do    0  85 

Gillott's  Mapping                                                         to    0  60 


LEAD  PENCILS. 
A.  W.  Faber's  Polygrades  (genuine). 

Hexagon  Gilt,  Nos.  1  2,  3,  4:  and  5  per  dozen   1  25 

Black  or  Red  Gilt,  round,  1.  2,  3,  4   do    100 

Black  or  Yellow  Gilt,  1,  2,  3,  4,  small   do    0  75 

One  box,  containing  7  Pencils,  for  Engineers,  sliding  ends  to  box...  0  75 

do  5  Pencils,  BB  to  H   0  75 

do  7  Pencils,  BBB  to  HH   0  90 

do  10  Pencils,  BBBB  to  HHHH   1  26 


LIST  OF  BOOKS 

ON 

Civil  Engineering,  Surveying,  &)0. 


*#*  Note.— Parties  ordering  should  either  send  drafts  or  postal  orders  on  New 
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post-office  where  mailed. 

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us  in  advance,  but  do  not  on  foreign  books,  so  that  it  is  necessary  to  include  ten 
per  cent,  additional  to  the  price  of  the  same  when  parties  desire  them  sent  by  mail. 

Orders  for  over  ten  dollars  will  be  sent  by  express  "  C.  O.  D. ; "  but  for  smaller 
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fii^  your  letter  before  mailm^. 

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Should  any  other  works  on  kindred  topics  be  desired,  we  will  furnish  them  at 
publishers'  prices. 


ARCHZTSCTUR&. 

Price. 

AEMENGAT7D,  AMOROUX,  and  JOHNSON— A  Complete  Course  of 
Mechanical  Engineering  and  Agricultural  Drawing.   Fully  illustrated  $10  00 

ASHPITEL — Treatise  on  Architecture,  including  the  Arts  of  Constructive 
Building,  Stone  Masonry,  Arch  Carpentry,  Roof  Joinery,  and  Strength  of 
Materials.   4to.   Illustrated   15  00 

BULLOCK'S  Rudiments  of  Architecture  and  Building.  250  engravings.  8vo.     3  50 

BULLOCK'S  American  Cottage  Builder.   75  engravings   3  50 

CLEVELAND  and  BACKUS'  Cottage  and  Farm  Architecture   4  00 

CUMMINGS  and  MILLER'S  Architecture,  including  Designs  for  Street 
Fronts,  Suburban  Houses,  and  Cottages,  and  with  a  great  variety  of 
details.   With  over  one  thousand  illustrations.   1  vol.,  large  4to   10  00 

CUMMINGS  and  MILLER'S  Modern  American  Architecture,  containing 
designs  and  plans  for  Villas,  Farm-houses,  School-houses,  Cottages,  City 
Residences,  Churches,  &c.,  1  vol.,  large  4to,  cloth   10  00 

DOWNING'S  Cottage  Residences.   8vo   3  00 

"  Country  Houses,  including  Designs  for  Cottages,  Farm-houses, 

and  Villas ;  with  remarks  on  the  best  modes  of  Warming 

and  Ventilation.    Finely  illustrated.   1  vol.,  8vo   8  00 

"          Landscape  Gardening  and  Rural  Architecture.   Finely  illus- 
trated.  8vo   6  50 

FIELD'S  City  Architecture.    1  vol.,  8vo   2  00 

HATFIELD'S  American  House  Carpenter.  A  Treatise  on  the  Art  of  Build- 
ing and  Strength  of  Materials   3  50 

HOLLEY'S  Country  Seats,  containing  Designs  for  Cottages,  Villas,  Man- 
sions, Railway  Stations,  &c.   1  vol.,  4to   6  00 

HUGHES'  Gardening,  Architecture,  and  Landscape  Gardening.  London. 
1  vol.,  8vo   7  50 

LOTH'S  Practical  Stair-Builder.  A  Complete  Treatise  on  the  Art  of  Building 
Stairs  and  Hand-rails.    Ukistratcd  with  30  original  plates.  1  vol.,  large  4to.   10  00 

LOUDON'S  Cyclopedia  of  Cottage,  Farm,  and  Villa  Architecture  and 
Furniture.   2,000  engravings.   1  vol.,  4to   21  GO 


LIST  OF  BOOKS.  167 

Price. 

ROBINSON  and  TEEDGOLD'S  Carpentry  and  Joinery.  With  plates   $3  00 

SLOAN'S  Homestead  Architecture.  Containing  40  Designs  for  Villas,  Cot- 
tages, &c   4  50 

SLOAN'S  City  and  Suburban  Architecture.   Containing  Designs  for  Public 

Edifices,  Private  Residences,  and  Mercantile  Buildings   15  GO 

SMITH,  Acoustics  of  Public  Buildings   0  75 

TOMLINSON,  Warming  and  Ventilation   1  50 

VAUX'S  Villas  and  Cottages.    With  nearly  500  engravings.   8vo   3  00 

WOODWARD'S  Country  Houses.   12mo   1  60 

"  Cottage  and  Farm  Houses.    With  178  original  Designs  and 

Plans  of  low-priced  Cottages  and  Farm  Houses   1  50 

"  National  Architect.  A  very  complete  work.  Fully  illus- 
trated.  1  vol.,  4to   10  00 

**  Rural  Church  Architecture,  containing  18  designs  by  dif- 
ferent Architects   12  00 

**  Suburban  and  Country  Houses.  With  70  Designs  and 
Plans,  and  numerous  examples  of  the  French  or  Cha- 
teau Roof .   150 

nniBa^By  Roors,  &c. 

BAKER'S  Long-Span  Railway  Bridges,   London   2  00 

CAMPIN,  Construction  of  Iron  Roofs   3  00 

CULLUM'S  System  of  Military  Bridges  in  the  United  States  and  Europe. 
1  vol.,  8vo   3  50 

HAUPT'S  Bridge  Construction.   With  practical  illustrations.   8vo   4  00 

"        Military  Bridges,  including  Designs  for  Trestle  and  Truss 
Bridges.    Bvo   6  50 

KUMBER'S  Cast  and  Wrought-iron  Bridges  and  Girders,  applied  to  Railway 
Stnictures,  &c.   With  58  rail-page  plates.   Imperial  4to   2100 

HUMBERTS  Cast  and  Wrought-iron  Bridges.  A  complete  Treatise,  includ- 
ing Iron  Foundations.   With  80  double  plates.   In  2  vols.,  4to   68  25 

MAYNARD'S  Bridges,  Roofs,  &c.,  in  Iron,  with  examples  from  actual  prac- 
tice.  London     2  50 

MERRILL'S  Iron  Truss  Bridges  for  Railways.  With  a  comparison  of  the 
most  prominent  Truss  Bridges.  Illustrated.   4to   5  00 

ROBINSON,  TREDGOLD  and  PRICE'S  Roofs  for  Public  and  Private 
Buildings.  Weale's  series  ,   0  75 

ROEBLING'S  Long  and  Short  Span  Railway  Bridges.  With  16  fine  copper- 
plates   25  00 

TJNWIN'S  Wrought  Iron  Bridges  and  Roofs.   London.  8vo   6  25 

WHIPPLE'S  Bridge  Building.   1  vol.,  12mo   5  00 

CONSTRUCTZOiaS,  STHErrGTH  OF  mATEHIAZ.S,  &c. 

ABELL'S  Machinery  Construction  and  Working   0  75 

"      Plates  to  the  above,  4to   3  75 

BAKER'S  Strength  of  Beams,  Columns,  and  Arches,  in  Cast  or  Wrought 

Iron  or  Steel.   London.   12mo   4  50 

BARLOW  on  the  Strength  of  Materials.  New  edition,  enlarged.   1  voL, 

8vo,  cloth   9  00 

BLAND'S  Arches,  Piers,  and  Buttresses   0  75 

BURGOYNE'S  Road-making  and  Macadamized  Roads   0  75 

BURNS'  Horse  Railways  for  Street  TrafBc,  &c.    London.   1  vol.,  12mo   0  75 

COLE'S  Contractor's  Book,  containing  Working  Drawings  for  Canal  and 

Railroad  Constructions   10  00 

BOBSON'S  Foundations  and  Concrete  Works   0  75 

"        Masonry  and  Stone  Catting   1  00 

"        Art  of  Building   0  75 

E ASTON* S  Horse  Railways;  their  Location,  Construction,  and  Manage- 
ment  2  00 

FAIRBAIRN'S  Application  of  Cast  and  Wrought  Iron  for  Building  Purposes. 

London.    8vo   8  00 

FEN  WICK'S  Mechanics  of  Construction,  including  theories  of  Strength  of 

Materials  for  Roofs,  Arches,  and  Suspension  Bridges.   London.   8vo   6  00 

FRANCIS,  Strength  of  Cast-iron  Pillars ;  with  Tables,  &e.   8vo   2  00 

GILLESPIE'S  Roads  and  Railroads;  their  Location,  Construction,  and 

Improvement   2  00 


168  LIST  OF  BOOKS. 

Price. 

GILLMORE'S  Limes,  Cements,  and  Mortars   $4  00 

BURNELL'S  Limes,  Cements,  and  Mortars   0  V5 

MAHAN'S  Civil  Engineering.   A  Treatise  on  Structures  and  Materials   4  00 

JERVIS'  Railway  Construction  and  Management   2  00 

TATE'S  Strength  of  Materials  as  applied  to  Tubular  Bridges,  Wrought  and 

Cast-Iro^  Beams,  &c.   London,  8vo   2  75 

WHILDIN'S  Strength  of  Materials  used  in  Engineering  Constructions.  12mo.  2  00 


DRAWING. 

APPLETON'S  Cyclopedia  of  Drawing   10  00 

BECKER'S  Letter  Book  and  Ornamental  Penmanship— a  series  of  Analytical 

and  Finished  Alphabets   4  00 

JOPLING'S  Practice  of  Isometrical  Perspective.  London.   8vo   1  50 

MAHAN'S  Lidustrial  Drawing,  comprising  a  Description  and  Uses  of  Draw- 
ing Instruments   3  00 

MINIFIE'S  Mechanical  Drawing,  including  an  Introduction  to  Isometrical 
Drawing  and  an  Essay  on  Linear  Perspective  and  Shadows.  Finely  illus- 
trated.   lvol.,8vo   4  00 

MINIFIE'S  Geometrical  Drawing— an  abridgment  of  the  above   1  50 

SMITH'S  Topographical  Drawing.   1  vol.,  Svo.   Plates   2  00 

WARREN'S  Manual  of  Projections   1  50 

Linear  Perspective   1  00 

"         Plane  Problems  in  Elementary  Geometry  ,   1  25 

"         Descriptive  Geometry   3  50 

"         Higher  Linear  Perspective   4  00 

General  Problems  of  Shades  and  Shadows   3  50 

WILLIAMS  and  PACKARD'S  Ornamental  Letter  Book   5  00 

GSOLOCir^  HaZNZNG,  AND  MSTAZ^IaURGlT. 

BAUERMAN— Metallurgy  of  Iron.   Containing  Outlines  of  the  History  of 

Iron  Manufacture,  Analysis  of  Iron  Ores,  &c.   12mo   2  50 

DANA'S  Manual  of  Geology,  treating  especially  of  American  Geological 

History.    1  vol   5  00 

DANA'S  Manual  of  Mineralogy,  including  Observations  on  Mines,  the 

Reduction  of  Ores,  &c   2  25 

FAIRBAIRN— Iron :  its  History,  Properties,  and  Processes  of  Manufacture..  4  50 
E-ERL'S   Metallurgy,  adapted  from  the  last  German  edition,  treating 

especially  on  Iron.   Vol.1   9  00 

LYELL'S  Principles  of  Geology.   1  vol.,  Svo   3  50 

"       Elements  of  Geology.   1  vol.,  Svo   3  50 

OVERMAN'S  Metallurgy,  comprising  Mining  and  Metallurgical  Operations. 

1  vol   5  00 

PEPPER'S  Play  Book  of  Metals,  including  Narratives  of  Visits  to  Coal, 

Lead,  Copper,  and  Tin  Mines   2  25 

PHILLIP'S  Mining  and  Metallurgy  of  Gold  and  Silver   15  75 

SILVERSMITH'S  Hand-book  for  Miners,  Metallurgists  and  Assayers,  with 

details  of  American  Mining  Practice   3  00 

URE'S  Dictionary  of  Arts,  Manufactures,  and  Mines.  3  vols   15  00 

H^TDRAUIiIC  ENaZNZIERZNG. 

BURNELL  and  SWINDELL,  Well  Sinking,  Boring,  and  Pump-work   0  50 

Hydraulic  Engineering   1  50 

DEMPSEY— Draining  Districts  and  Lands   0  75 

"         Drainage  and  Sewerage  of  Towns  and  Buildings   100 

EVANS'  Young  Millwright's  and  Miller's  Guide   2  50 

FRANCIS'  Lov/ell  Hydraulic  Experiments  on  Hydraulic  Motors,  flow  of 

water  in  weirs,  &c.   1  vol.,  4to   15  00 

FENWICK'S  Subterraneous  Surveying   1  25 

FRENCH'S  Principles,  Process,  and  Effects  of  Draining  Lands   1  50 

GLYNN'S  Water  Power  as  applied  to  Mills   1  25 

HEWSON'S  Embanking,  Rivers,  Levees,  &c   2  00 

HUGHES'  Waterworks  for  Cities  and  Towns   1  50 

PALLETTE— The  Miller,  Millwright,  and  Engineer's  Guide   8  00 

STEVENSON'S  Canal  and  River  Engineering   8  00 

TEMPLETON'S  Young  MUlwright's  and  Miller's  Guide   2  00 


LIST  OF  BOOKS. 


169 


FO0KET-3OOZI3.  TABlsHBn  &c. 

^  '  Price. 

BYENE'S  Pocket-Book  for  Railroad  and  Civil  Engineers   $175 

BURT'S  Key  for  Solar  Compass  >   2  75 

CROSS'  Engineer's  Field  Book   1  50 

GRISWOLD'S  Pocket  Companion  for  the  Field   1  50 

HASLETT'S  Engineer's  and  Mechanic's  Pocket-Book   2  50 

HASWELL'S  Engineer's  and  Mechanic's  Pocket-Book   3  00 

HENCK'S  Field  Book  for  Civil  Engineers   2  50 

MOLESWORTH'S  Pocket-Book  of  Formulae  for  Engineers   2  00 

NYSTROM'S  Pocket-Book  of  Mechanics  and  Engineering   2  50 

SCRIBNER'S  Pocket  Table  Book   2  00 

"           Engineer's  and  Mechanic's  Companion   2  00 

TEMPLETON'S  Millwright's  and  Engineer's  Companion   2  50 

TRAUT WINE'S  Excavations  and  Embankments   3  00 

Railroad  Curves   3  00 

WARNER'S  Theorems,  Tables  and  Diagrams  for  the  Computation  of 

Earthworks   6  25 


SURVZSirZNG  AND  SNGINSSRINa. 

ANDREWS'  Treatise  on  Agricultural  Engineering,  illustrated   1  50 

BAKER'S  Land  and  Engineering  Surveying   1  00 

GILLESPIE'S  Land  Surveying.   The  best  and  latest  work  published   3  00 

GILLESPIE'S  Higher  Surveying,  a  Treatise  on  Leveling,  Topography,  Min- 
ing, Surveying,  &c.,  just  published   2  50 

HAWES'  System  of  Rectangular  Surveying  employed  in  subdividing  the 
Public  Lands  of  the  United  States ;  being  a  Manual  of  U.  S.  Government 

Surveying.    1  vol.,  8vo     3  00 

GUMMERE'S  Surveying     2  50 

LAW  and  BURNELL'S  Engineering   2  25 

MENDELL'S  Military  Surveying  and  Instruments,  illustrated   2  00 

PLANE  TABLE,  and  its  use  in  Topographical  Surveying.   From  the  papers 

of  Coast  Survey.   Illustrated.   lvol.,8vo   2  00 

EANKINE'S  Manual  of  Civil  Engineering   8  00 

ROBINSON'S  Surveying  and  Navigation   2  50 

SIMMS'  Principles  and  Practice  of  Leveling     4  25 


THSATZSSS  ON  INSTRUMENTS. 

DICK— The  Telescope  and  MicroBCope   0  50 

GURLEY' S  Manual,  illustrated   0  50 

HEATHER'S  Treatise  on  Mathematical  Instruments   0  75 

HOGG— The  Microscope,  History,  Construction,  and  Application   3  50 

KENTISH  Box  of  Instruments  and  Slide  Rule,  or  Guide  to  Gauger,  Seaman, 

and  Student   1  25 

SIMMS'  Mathematical  Instruments   1  75 

WARREN' S  Draughtman' s  Instruments   1  25 


3M[ZSC&ZiZ.ANEOUS. 

APPLETON'S  Dictionary  of  Mechanics,  2  vols   20  00 

BOOTH  and  MORFIT,  Encyclopedia  of  Chemistry,  Practical  and  Theoret- 
ical.  Royal  8vo   5  00 

GREGORY'S  Mathematics  for  Practical  Men   3  00 

"          Nautical  Almanac,  with  Ephemeris   0  75 

inCHOLSON'S  Operative  Mechanic  and  Machinist   15  75 

OVERMAN'S  Mechanics,  for  the  Millwright,  Machinist,  Civil  Engineer,  and 

Architect   2  00 

ROSCOE,  Lessons  in  Elementary  Chemistry.   London,  12mo   1  50 

STETONSON  Lighthouses,  their  Construction  and  Illumination   1  50 

VAN  NOSTRAJSa)'S  Engineering  Magazine.  Per  No.,  50  cents ;  yearly,  $5. 


Table  of  Contents. 


Adjustments  of  Compass   16 

do           Vernier  Transit   38-42 

do           Surveyors'  Transit   60-62 

do           Solar  Compass  ,   76-79 

do           Leveling  Instrument   112-11.^ 

Adjusting  Socket   80 

Ball,  Compound  Tangent   44 

Builders'  Level   120 

Chains,  Surveyors'   128 

Chains,  Engineers'   129 

Chains,  steel   126-129 

Compass,  plain  •   14 

do      Vernier  •....<..*   23 

do      Kailroad   52 

do      Solar   64 

do      Miners'   123 

do      Pocket  ,                                                            .  124 

Cross  wire  ring  <   30 

Clctmp  and  tangent   36 

Drawing  Instruments   132-148 

Drawing  papers,  pencils,  colors,  <fcc   160-162 

Eye-piece,  how  composed   29 

Excellencies  of  the  Vernier  Transit  • « .  •   47 

Farm  Level   120 

General  matters  :  •   126 

Jacob-staff  socket   18 

Leveling  Instrument   107 

Leveling  Rods  «  •   121 

Lacquering.,..   127 


TABLE  OF  CONTENTS. 


Marking  pins  »   130 

Ma.'ieQs'  Level   120 

Micrometer  a*^-*   86 

Needle  Instruments.  «   50 

Object-glass,  how  composed  i*              ••••  29 

Parallax  instrumental   45 

Pinion  to  eye  glass   101 

Bcpairs  of  Compass   Id 

Solar  CompairS   64 

Solar  Compass,  proper   92 

Solar  Telescope  Compass  •   94 

Tangent  scale  on  sights   15 

Transit,  Vernier   28 

Transit,  Surveyors' .. ,   57 

Transit,  >]ngineers'   101 

Tripod  head,  light  >   58 

Tripod  head,  heavy   103 

Tripod  legs,  different  sizes  of   126 

Theodolite  axis   106 

Tapes,  measuring.   131 

Vertical  circle  •  36 

Vernier  Compass  •  23 

Vernier  transit   28 

Watch  telescope   105 

Weight  of  Compasses,plain   22 

do               Vernier   27 

do              Kailroad   55 

do               Vernier  Transit   49 

do               Surveyors'  Transit  •   62 

do              Solar  Compasses   99 

do              Leveling  Instrument  •   119 


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443  AND  445  Broadway,  New  York. 
D.  APPLETON  AND  COMPANY 

HAVE  RECENTLY  PUBLISHED 

j^Treatise  on  Land  Siarveying: 

THEORETICAL  AND  PRACTICAL. 

By  W.  M.  GILLESPIE,  LL.  D., 

professor  of  Civil  Engineering,  Union  College ;  Author  of  "  Manual  of 
Roads  and  Railways y"*^  SfC, 

1  Vol.  8vo.— 4Ji4  Pa-e«.— $3.00. 

WITH  FOUR  HUNDRED  ENGRAVINGS,   AND  A  MAP  SHOWING  THE  VARIA- 
TION OF  THE  NEEDLE  IN  THE  UNITED  STATES. 


Among  the  leading  peculiarities  of  the  work  are  these  : 

1.  All  the  operations  of  surveying  are  developed  from  only  five  simpU 
principles. 

2.  A  complete  system  of  surveying  with  only  a  chain,  a  rope,  or  any  sub- 
•titute,  is  fully  explained. 

3.  Means  of  measuring  inaccessible  distances,  in  all  possible  cases,  with  the 
chain  alone,  are  given  in  great  variety,  so  as  to  constitute  a  Land  Geometry, 
it  occupies  26  pages,  with  58  figures. 

4.  The  Rectangular  method  of  Compass -surveying  is  greatly  simplified. 

5.  The  Traverse  Table  gives  increased  accuracy,  in  one -fifteenth  of  the  space 
•f  the  usual  tables. 

6.  The  effect  of  the  changes  in  the  variation  of  the  needle,  on  the  resurvey  of 
eld  lines,  is  minutely  illustrated. 

7.  Correct  tables  of  the  times  of  elongation  of  the  North  Star  are  given; 
those  in  common  use  being  in  some  cases  nearly  half  an  hour  out  of  the  way. 

8.  The  adjustment  of  the  engineer  s  Transit  and  Theodolite  are  here,  for  the 
first  time,  fully  developed. 

9.  Methods  of  avoiding  obstacles  in  angular  surveying  occupy  24  pages,  ^ith 
35  figures. 

10.  Topographical  Mapping  is  fully  described,  with  illustrations. 

11.  Laying  out,  Parting  off,  and  dividing  up  Land,  are  very  fully  explained, 
and  illustrated  by  50  figures. 

12  The  most  recent  improvements  in  the  method  of  surveying  the  Public 
Lands  of  the  United  States,  with  the  methods  used  for  marking  "  corners,''  are 
minutely  described  from  ofiicial  authorities. 

A  double  object  has  been  kept  in  view  in  the  preparation  of  the  volume,  viz : 
to  make  an  introductory  treatise  easy  to  be  mastered  by  the  young  scholar  or 
the  practical  man  of  little  previous  acquirement,  the  only  pre-requisites  being 
Arithmetic  and  a  little  Geometry;  and,  at  the  same  time,  to  make  the  instruc- 
tion of  such  a  character  as  to  lay  a  foundation  broad  enough  and  dc»p  enough 


Advertisement. 


for  the  most  complete  superstructure  which  the  professional  student  may  subs©* 
quently  wish  to  raise  upon  it. 

The  volume  is  divided  as  follows : 

Part  I.  General  Principles  and  Fundamental  Operations.  II.  Chain  Sur- 
veying. III.  Compass  Surveying.  IV.  Transit  and  Theodolite  Surveying, 
V.  Trigonometrical  Surveying.  VI.  Trilinear  Surveying.  VII.  Obstacles  iu 
Angular  Surveying.  VIII.  Plain  Table  Surveying.  IX.  Surveying  without 
Instruments.  X.  Mapping.  XI.  Laying  out,  Parting  off,  and  Dividing  up 
Lands.    XII.  United  States  Public  Lands. 

Appendix. — A.  Synopsis  of  Plain  Trigonometry.  B.  Demonstrations  of 
Problems.    C.  Leveling. 

Tables. — Chords  for  Platting.  Latitudes  and  Departures,  Natural  Sines 
and  Cosines. 


EXTRACTS  FROM  LETTERS. 

From  Prof.  Chas.  W.  Hackley,  Columbia  College,  New  York : 

Prof.  Gillespie's  work  is  the  most  complete  one  in  our  language  on  th« 
branches  of  surveying  of  which  it  treats." 

From  Prof.  D.  H.  Mahon,  West  Point  Academy: 
*'I  have  received  Prof.  Gillespie's  work  on  Surveying,  which  you  have  had 
the  kindness  to  send  me.  In  this  treatise.  Prof.  Gillespie  has  given  another 
evidence  of  his  practical  acquaintance  with  the  wants  of  the  teacher  and  pupil 
in  his  specialty,  and  of  his  ability  to  meet  them.  His  work,  which  presents 
several  new  features  in  its  plan,  is  written  with  such  plainness,  and  illustrated 
with  such  copiousness  of  diagram  and  detail,  as  ciinnot  fail  to  render  the  subject 
of  easy  attainment  to  the  must  ordinary  comprehension.'^ 

From  Prof.  E.  S.  Snell,  Amherst  College: 

Please  accept  my  thanks  for  the  copy  lately  received  of  Prof.  Gillespie's 
Surveying.  I  very  much  admire  its  systematic  character,  its  completeness  and 
fullness,  and  its  adaptedness  in  all  respects  to  the  wants  of  the  teacher,  the 
pupil,  and  the  practical  Surveyor.  I  have  seen  no  work  which  can  at  all  b« 
brought  into  comparison  with  it." 

From  Prof.  Aug.  W.  Smith,  Wesleyan  University: 
**0n  examination,  I  find  it  the  most  full  and  complete  of  any  work  on  Prac- 
tical Surveying  with  which  I  am  acquainted.    It  furnishes  information,  minute 

and  specific,  on  all  points  which  are  likely  to  occur  in  practice  

I  know  of  no  better  w,ork,  or  one  better  adapted  to  the  wants  of  those  who  have 
not  the  aid  of  the  living  teacher." 

From  J.  W.  Andrews,  President  of  Marietta  College,  Ohio. 
^*  From  my  knowledge  of  the  author,  I  was  prepared  to  expect  a  work  of  de- 
aided  excellence,  and  certainly  I  have  not  been  disappointed.     ....  I 
shall  take  great  pleasure  in  recommending  it  to  all  who  wish  a  full  knowledge 
of  surveying." 

From  A.  C.  Roe,  Principal  of  Cornwall  Collegiate  School: 
I  thank  the  author  for  the  time  and  labor  it  has  saved  me,  and  express  the 
great  satisfaction  with  which  I  have  used  it.  Valuable  in  its  plan  and  the 
happy  manner  in  which  the  principles  of  the  science  are  unfolded,  it  is  still 
more  so  in  those  practical  hints  which  I  have  seen  in  no  other  work,  and  which, 
though  of  the  greatest  importance  even  to  a  beginner,  I  learned  myself  only  aftet 
a  long  time,  and  very  considerable  experience." 


THE  GREAT  BOOKS  OF  THE  MY. 


QUACKESBOS'S  ARITHMETICS. 

A  Primary  Arithmetic.    Beautifully  illustrated ;  carries  the  beginnei- 
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An  Elementary  Arithmetic.    Reviews  the  subjects  of  the  Primary  ia 
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144  pages.    60  cents. 
A  Practical  Arithmetic.     Prepared  expressly  for  Common  Schools, 
giving  special  prominence  to  the  branches  of  Mercantile  Arithmetic. 
12mo.    336  pages.  $1. 
A  Higher  Arithmetic.    In  preparation. 
A  Mental  Arithmetic.    Nearly  ready. 

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plied with  a  great  variety  of  examples;  brief  and  exact  in  their  rules; 
condensed  and  searching  in  their  analyses;  teach  the  methods  actually 
used  by  business-men;  up  to  the  times;  oblige  the  pupil  to  think  in  spite 
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ligent and  not  a  mechanical  process;  the  only  books  that  a  progressive 
teacher  can  afford  to  use;  perfect  text-books;  with  no  defects.  This  is 
what  teachers  say  of  our  new  Series  of  Arithmetics  (read  their  opinions  on 
the  opposite  page).  These  are  the  features  that  are  introducing  them  into 
schools  everywhere. 

Look,  in  particular,  at  the  Practical.  Its  definitions,  rules  and  analyses 
are  free  from  unnecessary  words;  its  methods  are  the  shortest  possible;  its 
mode  of  developing  the  subject  is  pronounced  unequalled.  Above  all,  it  is 
the  only  hook  that  recognizes  all  the  important  financial  changes  of  the  last 
five  years.  The  prices  given  in  the  examples  are  those  of  the  present  daj^ ; 
the  difference  between  gold  and  currency  is  taught;  the  rate  of  duties 
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examples  given  to  show  the  comparative  results  of  investments  in  them. 
These  are  matters  that  every  one  should  understand,  and  no  Arithmetic 
that  ignores  them  sho^dd  he  allowed  to  remain  in  the  hands  of  our  youth. 

Quackenbos's  Arithmetics  are  used,  to  the  exclusion  of  all  others,  in  the 
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institutions  are  introducing  them.  After  examining  them,  teachers  ar« 
unwilling  to  use  any  others. 


aUACKENBOS'S  ARITHMETICS. 

PERFECT  TEXT-BOOKS," 

WITH  NO  defects:' 

so    SAY    SOME    OF   OUR    BEST  TEACHERS, 
READ  THEIR  OPINIONS. 


Johv.  C.  Harkness,  Principal  of 
the  Delaware  State  Normal  School : 
^'  We  hare  carefully  examined  the 
Practical  Arithmetics  before  the 
American  people,  and  to-day  feel 
that  said  people  owe  a  debt  of  gra- 
titude to  Mr.  Quackenbos  for  hav- 
ing perfected  a  text-book  in  that 
,  department  of  education." 

E.  D.  Kingsley,  Superintendent 
Public  Schools,  Columbus,  0. : 
have  looked  in  vain,  for  the  last 
ten  years,  for  such  a  work.  I  re- 
gard it  (the  Primary)  as  the  most 
desirable  treatise  of  the  kind  that 
has  ever  been  published. 

John  C.  Ridpath,  Superintendent 
of  Schools,  Lawrenceburgh,  Ind.  : 
I  have  examined  the  Arithme- 
tics, and  in  some  particulars  think 
them  superior  to  any  yet  published. 
Especially  do  I  regard  the  Primary 
as  THE  BEST  which  I  have  seen. 
The  illustrations  cannot  be  sur- 
passed :  as  a  manual  for  the  object 
method,  it  is  just  the  thing." 

David  Copelaud,  President  Hills- 
boro  (Ohio)  Female  College:  I 
consider  Quackenbos's  Practical 
Arithmetic  superior  to  any  similar 
work  published  in  this  country. 
The  subjects  are  all  treated  in  a 
superior  manner." 

Talter  Smart,  Principal  Class. 
Academy,  Alleghany,  Pa. :  I 
consider  Quackenbos's  Practical 
the  best  Arithmetic  I  have  ever  had 
in  my  hands.'' 


Geo.  W.  Todd,  Principal  High 
School,  Edgartown,  Mass. :  With 
a  class  of  thirty  now  in  your  Prac- 
tical Arithmetic,  I  cheerfully  say 
I  never  saw  its  equal  for  the  place 
it  is  designed  to  fill." 

Chester  Holcombe,  Prin.  Public 
School  No.  11,  Brooklyn,  N.  Y.  : 
They  have  been  in  use  among 
the  twelve  hundred  scholars  of 
whom  I  am  in  charge,  for  the  past 
three  months,  and  thus  I  have  had 
ample  opportunity  to  judge  of  their 
merits.  I  am  confident  there  is  no 
other  series  of  text -books  on  that 
subject  of  an  equal  degree  of  excel- 
lence. In  the  Primary  I  have 
found  an  unequalled  manual  for 
object  teaching." 

Henry  H.  Fay,  Principal  of  Eng- 
lish and  Class.  School,  Newport, 
R.  I. :  It  is  about  six  months 
since  I  introduced  Quackenbos's 
Practical  Arithmetic  into  my 
school,  and  I  do  not  hesitate  to 
pronounce  it  the  best  I  have  ever 
used.'' 

Sister  M.  Alfred,  Superioress  St. 
Francis  School,  Joliet,  III. :  «^  We 
have  critically  examined  Quack- 
enbos's Primary  and  Elementary 
Arithmetics,  and  pronounce  them 
the  most  excellent  works  of  the 
kind.  We  are  now  using  them 
with  entire  satisfaction  to  both 
ourselves  and  our  pupils.  No 
other  books  than  Quackenbos's 
shall  henceforth  be  used  in  our 
schools.'^ 


We  mail  specimen  copies  of  these  standard  hooks  to  any  teacher  or  school 
dfficer  on  receipt  of  one -half  the  abovii  prices.  A  careful  examination  is  all 
we  ask.  Why  use  inferior  books,  when  the  best  are  within  reach  ?  Thi 
most  favorable  term>s  made  for  introduction.  Address 

D.  APPLETON  &  Co.,  Publishers, 

443  «&  445  Broadway,  New  York* 


178 


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SOEIBKER'S 
ENGINEERS'  AND  MECHANICS'  COMPANION. 

Comprising — 

United  States  Weights  and  Measures,  Mensuration  of 
Superfices  and  Solids,  Tables  of  Squares  and  Cubes,  Square 
and  Cube  Eoots,  Circumference  and  Areas  of  Circles.  Tbe 
3Iechanical  Powers  ;  centres  of  gravity,  gravitation  of  bodies, 
pendulums,  specific  gravity  of  bodies,  strength,  weight,  and 
crush  of  Materials,  water  wheels,  hydrostatics,  hydraulics, 
statics,  centers  of  percussion  and  gyration,  friction,  heat, 
tables  of  the  weights  of  metals,  pipes,  scantling,  &c.,  &c. 
Steam  and  Steam  Engine. 

SIXTEENTH  EDITION.     REVISED  AND  ENLARGED. 

By  J.  M.  SCRIBNER, 

Author  of    Engineers'  Bocket  Table  JBooh.,''  &c,,  &c, 
BOUND  IN  TUCK.  GILT. 

Eecommended  in  the  highest  terms  by  the  profession 
throughout  the  United  States. 

Copies  sent  to  any  address,  prepaid,  carefully  wrapped 
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179 


SOEIBKEE'S 

ENGINEERS',  CONTRACTORS',  AND  SURVEYORS' 

POCKET  TABLE  BOOK. 

Comprising — 

Logaritlims  of  Numbers,  from  1  to  10,000 ;  Points  of  the  Compass ;  Logarithmic 
Sines,  Tangents,  and  Secants,  to  every  point  and  quarter-point  of  the  compass ; 
Hyperbolic  Logarithms;  Geographical  Miles  in  a  Degree  of  Longitude;  Velocity 
and  Force  of  the  Wind ;  Sines  and  Tangents ;  Traverse  Table ;  Table  of  Natural 
Sines ;  Table  of  Natural  Tangents ;  Areas  of  the  Zones  of  a  Circle ;  Areas  of  the 
Segments  of  a  Circle ;  Lengths  of  Circular  Arcs ;  Lengths  of  Circular  Arcs,  Radius 
being  Unity ;  Proportions  of  the  Lengths  of  Semi-elliptic  Arcs  ;  Proportions  of  the 
Lengths  of  Circular  Arcs ;  Demonstration  of  the  Prismoidal  Formula ;  Explanation 
of  Excavation  Tables ;  Tables  of  Excavation  and  Embankment,  First  Series  ;  Tables 
of  Excavation  and  Embankment,  Second  Series  ;  Tables  of  Excavation  and  Embank- 
ment, Third  Series ;  Circumferences  and  Areas  of  Circles  by  Eighths ;  Squares, 
Cubes,  Square  and  Cube  Roots ;  Circumferences  and  Areas  of  Circles  by  Tenths  ; 
Weight  of  a  Lineal  Foot  of  Square  Iron  ;  Weight  of  a  Lineal  Foot  of  Round  Iron ; 
Weight  of  a  Lineal  Foot  of  Flat  Bar  Iron ;  Weight  of  Cast  Iron  Pipe ;  Weight  of 
Malleable  Iron,  Copper,  and  Lead  Pipe ;  Weight  of  Cast  Iron  Solid  Cylinders ; 
Weight  of  Cast  Iron  and  Lead  Balls ;  Number  of  Nails  and  Spikes  to  the  Pound ; 
Table  on  the  Strength  of  Columns  of  Wood ;  Table,  showing  the  Dimensions  of 
Cast  Iron  Columns  for  sustaining  a  given  weight  with  safety ;  Weight  of  Lead  and 
Copper  Pipes ;  Table  of  the  Strength  of  Materials ;  Hints  about  laying  out  Curves ; 
Table  of  the  quantity  of  Land  for  Railroads  and  Canals ;  Explanation  of  the  quantity 
of  Land  for  Railroads  and  Canals ;  Difference  of  Level ;  Curvature  of  the  Earth ; 
Earthwork  in  Canals ;  Angles  of  Slopes  in  Cuttings  or  Embankments ;  Mathematical 
Diagrams ;  Diagram  for  laying  out  Curves ;  Inclined  Planes ;  Longitude  affecting 
Time ;  Experiments  on  the  Strength  of  various  species  of  Timber ;  Stiifness  of 
dilFerent  Woods ;  Comparative  Strength  of  Ropes  and  Chains ;  Weight  in  lbs.  of  a 
Foot  in  length  of  Cast  Iron ;  Weight  of  a  Cubic  Foot  of  Various  Subst,ances ; 
Scantling  and  Timber  Measure,  &c.,  &c.,  &c. 

This  book  is  largely  used,  and  no  better  proof  of  its  usefulness  can 
be  given  than  that  fact.  Copies  sent  to  any  address,  prepaid,  on 
receipt  of  $2.00,  by 

HAMEESLEY  &  CO., 


Publishers,  Hartford,  Conn. 


